Original XK tyres

[Longstone]

I was surprised to see this picture in Practical Classics of an XK120 fitted with Dunlop B5 tyres. i thought they fitted 600H16 Dunlop RS5

https://www.facebook.com/longstonetyres/photos/a.212924405440944/2058710830862283/?type=3&eid=ARDbokzaRQpb6jFiQO5dvwHZQ_hJeMa75_6ShTIcZGTc0_s7o_60lme96R4mPCB6GjVBXmtHU4KVQ0NF&xts%5B0%5D=68.ARDV7eBrmDBf7k3eMQ_Vwv3s1GU4xRL5OP4zaduip6blHXWdva7qeNTEulMMgfJFDHf8gOYJDWPpAuPW2Q9RCDgakasnhNtERv_4GnOG7S6h1tzsObLEai7TZvWiseyT5ywPCZqCqyVfT-fETB1hr0uyS6lbWj0PEk_PvaJInbNyuFRpnGv0qF5FDJv0Y7JZVWTj-GjPXDEGXdX5x43ss-MbFNQ&tn=EHH-R

[Mike_S (Mike Spoelker)]

Looks like RHD. What was the first public show car? Early prototype, 66001? The windscreen pillar base doesn’t look right for the alloy cars? White steering wheel? For sure, someone here will already know which car this is.

[PhilW]

Years ago we restored an early 120 rd. The owner made us paint the white steering wheel black.

Phil.

[CP120]

Hi Mike:

From the photo I would guess that the car pictured is HKV 455 (660001) which was the car featured at the Earls Court Motor Show Oct., 1948. That car, painted bronze was RH drive and had a white steering wheel. I note the car carries a price on the windscreen in pounds sterling. The early show car and the first LH drive car (670001) both had the same straight windscreen pillars exactly as shown in the black and white photo. Regarding the tyre query, I thought Dunlop R5s were a racing tyre?

Chris.

[Roger_Payne]

A few comments about DUNLOP tyres, after having a good effort at researching the subject recently.

1. The pictured car at the Oct 1948 Earls Court Motor Show is most definitely 660001, but as far as I can tell from this photo it is most probably fitted with DUNLOP FORTE tyres, of 6.00-16" XK120 size, with the ROADSPEED tyre not yet available.
   My understanding is that DUNLOP in response to Jaguar pressure, then developed a new tyre more suitable for road use up to the XK120s claimed 120 mph capability, and that tyre was on introduction called the ROADSPEED and fitted to the first customer delivered XK120s from 1949 on.

2. The initial or first generation DUNLOP ROADSPEED looked identical re sidewall and tread pattern to the FORTE tyre pictured, but had upgraded internal construction to suit higher speed requirement of the XK120, bearing in mind that prior to the early 1960s, tyre manufacturers and Government Regulation hadn’t yet introduced controlled and mandatory tyre Speed Ratings, such as the S, H, V etc symbols that post early 1960s was legally required to be shown within the tyre-size marking moulded into the sidewall.

3. The initial DUNLOP ROADSPEED was superseded by the improved/upgraded DUNLOP ROADSPEED RS4 in about 1956/7, and in Jaguar terms was first offered as original equipment on the XK150, still of course in 6.00-16 size and still no speed rating. These became more generally known as the DUNLOP RS4 with the RS = Roadspeed of course, and no idea what happened, if anything to RS2 and/or RS3 which may have been internal development tyres, or internal identification only, but never manufactured/sold retail actually marked/identified as RS2 or RS3.

4. The RS4 was short-lived, and was in turn superseded by the DUNLOP RS5 in 1959, and still not yet showing any speed rating symbol, but were now original the equipment tyres for XK150 in 6.00-16 size and from March 1961 on for E-types in 6.40-15in size.

5. The E-types claimed 150 mph top speed further pushed the envelope, with DUNLOP still not yet making radial ply tyres, and Jaguar not prepared to fit the then after-market available Michelin ‘X’ radial tyre, that had been introduced by Michelin in the late 1940s.

6. The initial Dunlop Radial tyre - the SP41 was only rated (by DUNLOP) as suitable for ‘up to 125 mph’, as was the same age cross ply RS5 so was only first offered by Jaguar as optional on Mark 10 and Mark 2, but not E-type (and of course never on any earlier model XK)

7. The Dunlop radial was further developed to become an SP41H now rated to 130mph+, and from about 1968 to become the SP Sport, also rated by Dunlop as suitable for 130 mph +.(Remember the advertising for the new Dunlop (SP Sport) Aquajet as being developed especially for the new Jaguar XJ6 model). Indeed from about 1963/4 the tyre industry/government regulation had now introduced the S and H code speed-rating (and mandatory marking on the tyre sidewall size moulding). Later on, the higher V tyre rating code was added. Cross-ply tyres, such as the still made RS5 didn’t initially require to be speed rated/marked, but later on they did - exact date not yet ascertained.

8. So when you see a DUNLOP RS5 shown as 600H16 (or similar with the ‘H’ speed rating included’ this is a cosmetic tread-pattern/sidewall apperance reproduction of the 1960s original DUNLOP RS5 600-16 tyre, albeit built to higher more modern standards than the original RS5s, let alone the original XK120/140 DUNLOP ROADSPEED and the XK150 original RS4.

9. But note, the Jaguar factory never supplied any XK120, XK140 nor XK150 with radial ply tyres, albeit the Michelin ‘X’ radial was readily available aftermarket in 6.00-16 size. This was before the agreed 1960s convention of showing metric width/inch diameter and the letter ‘R’, thus 185-R15 (or similar) for radial ply tyres, with the inch width/inch diameter 6.00-16 size convention restricted to cross-ply tyres.
   See attached photo of sidewall marking on a 1950s manufactured 6.00-16 Michelin X tyre before the inch/metric size convention introduced; an unused ‘spare wheel tyre’ on an XK140 imported to Australia in the 1960s from USA.

10 Pirelli Cinturato came along later, but still second after Michelin, and didn’t offer XK size tyres until much later, exact year not established but certainly by the early 1970s, and certainly back then were seen as a rapidly wearing/soft tyre on XKs, but were rat least available in XK and E-type sizes, where 16 inch radials in particular were even then, most scarce (at least in Australia). I have no recent experience with Pirelli Cinturato on XKs - given 1970s experience - so maybe they have improved, as sadly my 185R16 tyre of choice for XKs through until a c10 years ago was the New Zealand made FIRESTONE Cavalino, no longer available because of parent company USA DOT marking requirements if made in USA, after their NZ Factory closed.

But tyres are a personal choice, that you really cant go wrong with the ‘main’ well known brands, but I would still be cautious buying any of the proliferation of obscure Asian brands, but excluding the well known Japanese and Korean brands.

I do note that if you want a modern extremely well regarded and well made Radial tyre, that is period correct brand and appearance for an XK (even if not made the same as in the 1950s) then the Michelin ‘X’ with ‘Stop’ tread pattern is still made/offered in 16in XK size. But for those into Concours, radial ply tyres of any brand, are NOT considered authentic, thus are a major deduction. Similar situation with 3.8 E-types, radial ply tyres of any brand are not authentic, despite todays Jaguar factory claiming authentic rebuilds/reproduction 3.8 E-types, offering ‘Customer Choice’ upgrades.

[Longstone]

“The E-types claimed 150 mph top speed further pushed the envelope, with DUNLOP still not yet making radial ply tyres, and Jaguar not prepared to fit the then after-market available Michelin ‘X’ radial tyre, that had been introduced by Michelin in the late 1940s.”

Or the Pirelli Cinturato (also called Cintura) developed in 1952. the Michelin X was not so much used on Sports cars. For instance cars like the Lancia Aurelia, the more pedestrian models fitted Michelin X and the Sporting cars fitted Cinturato. As did the AC Cobra 289, Ferrari, Maserati & Aston Martin of the later '50s and '60s.

“The initial Dunlop Radial tyre - the SP41 was only rated (by DUNLOP) as suitable for ‘up to 125 mph’, as was the same age cross ply RS5 so was only first offered by Jaguar as optional on Mark 10 and Mark 2, but not E-type (and of course never on any earlier model XK)”

However the Pirelli Cintura High Speed, In Jaguars view did not demand this speed restriction. Not did the high performance Italian cars that were fitting them in period. In the 1963 Jaguar Bulletin Jaguar called it the “Cintura High Speed” when they said “Dunlop SP tyres are now available for the “E” type and Mark 2 models.”
they also said “but they are not yet available in the size required for the Mark 10 model” at this point a tyre of the section 205 had not been developed that was able to withstand this sort of power; until Pirelli developed the Cinturato CN72 in 1964. you will notice all the bigger performance cars, on radials, of the later '50s and early '60s fitted 185 section Pirelli Cinturato. generally speaking 185R16 in the '50s then cars like the Ferrari 250 GTE moved onto 185R15 where the earlier Ferrari 250 were fitting 185R16 Cinturato, as did Aston Martin in the early '60s towards the end of the production of the DB4 when they moved onto 15" wheels.
it wasn’t until 1964 that a tyre was produced with a 205 section (such as needed by the MK10) that was able to cope with these super cars. and to a nerd like me you see most of the production of the Italian Super cars like the Ferrari 330, Maserati Mistral and Lamborghini Muira fitting 205R15 Cinturato CN72 from 1964 onwards, moving from fitting 185VR16 CA67 onto fitting 205VR15 CN72 having the same diameter, with a bigger cross section & greater foootprint

"10 Pirelli Cinturato … didn’t offer XK size tyres until much later, "

Maserati were fitting 185R16 Pirelli Cinturato in the '50s as were Ferrari on the 250. If you wanted radial tyres on your David Brown Aston Martin in the '50s they fitted Cinturato on their 16" wheels in the size 185. the same as the XK

This comment also does not ring true with the majority of people i talk to who ran these cars in period.

" and certainly back then were seen as a rapidly wearing/soft tyre on XKs, "

I believe they were seen as the best sports car tyre of the period.

We sell lots of these 16" Cinturatos to '50s cars, many to XK cars. Not only because they are the only period correct sports car tyre that has the capability of with standing the speeds of these cars currently. they were in the '50s too. They because these are the best handling tyres for these cars as well.

Yes the Michelin X is also period Correct, but it is not V rated, and wasn’t in period either. The 185SR16 Michelin X is a lovely tyre to drive these cars on, but it is not a Sports car tyre. The Michelin Pilote X is also a great high performance tyre but not actually period correct, and a little wide really. but great at high speed.

On the subject of the Michelin X. It was the first radial tyre made by Michelin, which they made initially only for 400mm wheels. Pirelli started making radial tyres in inch format, and one of the first sizes was 185VR16. (Also the other 155R15 for the little Alfa Giulietta )

In the XK club magazine a few months ago there were also some incorrect claims in an article about tyres about the dimensions. Radial tyres are increasingly a different shape to crossply. as the development of the radial has moved along they have had increasingly wider foot prints in relation to the width of the section of the tyre, which is why the wholey new 185VR16 Avon TurboSteel tyre is completely the wrong shape for a '50s car for road use, though pretty good on the track. But when you look at the dimensions of the tyres and when you see them in flesh you will see that the 2 radial tyres that suit '50s cars on 16" wheels are the 185SR16 Michelin X & the 185Vr16 Pirelli Cinturato.

This picture shows the dimentions as clearly as i have managed to do it. but sadly when i took this photo i only had a 600H16 Avon TurboSpeed not the Dunlop RS5. (however both the 600H16 RS5 & 600H16 TurboSpeed claimed the same diameter in their specification.)

[Wiggles (Paul Wigton)]

@PhilW

The owner made us paint the white steering

Homer Simpson Doh sound effect

[Roger_Payne]

The subject of this thread is ORIGINAL XK TYRES.
Longstone, and sorry I don’t recall your personal name, just your business name, but it would be nice to get back to subject thread, rather than being a marketing promotion for retailing new XK suitable tyres, albeit a most valuable necessity for XK owners. And I do like your commercial advertisements in XK Gazette, where I think I have seen your ‘group photo’ before.

Your original comment that you thought the 1948 Earls Court XK120 was fitted with 600H16 Dunlop RS5 tyres, was simply so wrong in so many respects, and surprisingly so, for someone claiming tyre expertise, that I saw fit to correct the many errors, albeit admittedly somewhat long winded - but this is a topic of a lot of interest to a number of XK authenticity researchers, and XK owners, that I thought worth detailed comment. Those not interested in such authenticity detail, simply can delete.
Your ‘thought they fitted 600H16 Dunlop RS5’ Tyres statement…………

The original tyres fitted to the first, and all XK120s was the DUNLOP ROADSPEED, albeit from 1952 onwards the DUNLOP ROADSPEED ‘White wall’ tyre was optional, and indeed a popular choice in USA. The RS5 was a much later development of the ROADSPEED, and indeed is believed not to have been introduced until 1959, but still made in the 1960s, and indeed was the standard tyre offered from 1961 when the E-type was introduced, and remained so, until Jaguar eventually offered the Dunlop SP41H radial ply tyre for home-market and European market cars from 1964 onwards.

You say 600H16 tyres for an XK120. Again NO. The ‘H’ symbol is a Tyre Industry/Government Regulation requirement of the tyres ‘certified’ speed rating as introduced in about 1963/4. This symbol and what the symbol stands for simply did not exist for XK120 era tyres, nor indeed XK140 nor XK150 as applicable to DUNLOP ROADSPEED, RS4 and original RS5 tyres. When you see a Dunlop RS5 tyre with this ‘H’ symbol, that identifies the tyre as a more modern classic reproduction tyre, not sure when first offered by Dunlop, but certainly readily available in 1980s/90s and up to recently - now discontinued (but you will/should be better aware being in the new classic tyre business)

And having said that the 600H16 RS5 is a modern reproduction of the 1959 onwards 6.00-16 RS5, although marked/identified as an RS5 it is a reproduction in external appearance only (apart from the sidewall markings - modern laws do not allow a new tyre to replicate the 1950s markings). Its internal construction is however is improved by more recent tyre technology, and indeed is most probably a ‘better’ tyre than the 1959 original.

The PIRELLI subject is of course a red-herring to the subject title - ORIGINAL XK TYRES, albeit clearly of marketing/retailing interest. But being of XK and E-type ‘period’ interest, if not ‘original equipment’ interest it would be great if you did indeed have some proof of 1950s/60s period Pirelli Cinturato tyres, rather than simply the modern reproduction Cinturato labelled tyres as currently retailed to classic car owners, including XK owners. There are indeed gaps in current research knowledge of the 1950s/60s original Cinturatos, so any PROOF you may have, rather than sweeping generalisations, would be of immense help.

First up - can you provide any photos of the side wall markings of an XK size 1950s made Pirelli Cinturato.
There are a number of critical aspects to this request, and off the top of my head, without checking research notes……

1. Tyres made to suit an XK would most probably be made in the Pirelli UK factory, and necessarily of course in a 16" rim diameter size. Tyres made for Italian/French cars in the 1950s invariably (all ?) were made with metric rim diameters.

2. I understood that the Pirelli UK factory first made CINTURA tyres, and not CINTURATO, and not sure when they first made CINTURATO as had been already made for many yeras in Pirellis factories in Italy (and Spain etc). Can you clarify.

3. Regardless, any tyre made by Pirelli (or anyone else) in the 1950s simply just did not have any industry/regulatory agreed/mandated speed rating of S or H on them, with ‘manufacturers claims’ of speed suitability simply that - manufacturers claims. These S and H regulatory imposed speed ratings/and requirement to be visibly moulded into tyre side wall just did not happen until c1963/4.

4. The earliest Pirelli Cinturatos made in the XK 185-16 size, after the introduction of mandatory speed ratings, and markings, were rated ‘S’ and not ‘H’ - see attached photo of an original 1960s/70s Pirelli Cinturato….

   
   
   
   

5. If you have similar photos of the side wall markings of what you claim was a 1950s made XK size Pirelli Cinturato, I would love to see. Based on current research, it most definitely will not have any S (or indeed H) speed rating. It will not have any ‘R’ symbol for Radial, as I believe that was also introduced at same time as the mandatory speed-rating symbol in the early 1960s. And I seriously doubt it will show a 175 or 185 metric width, but more probably as per all DUNLOP and MICHELIN 1950s tyres when on inch size rims, also an INCH size width - so 600-16 or 6.00-16 or similar

6. And back to your modern reproduction Cinturatos, similar in external apperance only to the 1950s/60s originals (apart from side wall marking), these are clearly significantly improved tyres, as amongst other likely construction/materials improvements, they now I believe have a speed rating higher than their initial 1960s/70s ‘S’ rating.

7. I repeat my earlier comment. My first hand experience with ‘original’ 185SR16 Pirelli Cinturatos on an XK150 I owned for some years in the 1970s was not favourable relative to the then also available Michelin ‘X’, but still for my purposes much improved over the then available ‘cross-ply’ tyres. They were relatively soft and wore/scrubbed quickly with spirited driving on public roads. I don’t have any first hand experience with modern reproduction tyres still called/branded Pirelli Cinturato - but then go back to the title of this theme - ORIGINAL XK TYRES.

8. So again - love to see any PROOF you have with respect to 1950s Pirelli Cinturato tyres - and no modern reproduction red-herrings please.

[Bob_K1 (Bob Knijnenburg)]

Roger,

Excellent summary (as usual). You may remember that we discussed the subject before and I would like to quote my own text (published in some magazines) regarding the British made Cintura tyres, to put some points right. It doesn’t change the overall timeline on Pirelli’s. I’ve highlighted some of the dates and dimensions to further complete your story.

The only reason why Pirelli UK didn’t use the name Cinturato, is given in a 1962 advertisement: “Cintura, for the curious, is from the Latin = meaning Belt” but that doesn’t really help……

QUOTE:

The range of Cintura sizes was “cautiously” extended over the years and although the Cintura became known as one of the best tyres for fast sportscars, the correct sizes for the larger British sportscars were only launched in 1962 and even dedicated for the UK market. After Pirelli had made the first Cinturato’s in sizes 185 x 15 and 185 x 16 in their Italian factory around 1960 (for Ferrari and Maserati), the same Cintura sizes were introduced in the UK, but locally manufactured in Burton-on-Trent (although using Italian made moulds).

These Cintura tyres were suitable for speeds of “only” 200 km/h (125 mph). From June 1962 onwards, Pirelli UK manufactured a new Cintura tyre in the same sizes with the extension HS (High Speed) . This tyre had a nylon carcass and special textile belt under the tread, now suitable for speeds of up to 240 km/h (150 mph).

In the July 1962 issue of Motor Sport magazine, we read: “ The ordinary Cintura cover is suitable for speeds up to 125 m.p.h. but at Burton-on-Trent a new Cintura HS tyre is now in production . This has a nylon instead of a rayon casing, a specially constructed textile belt and a tread compounded to give better bonding to the casing. It is safe for continuous driving at up to 150 m.p.h. At present only two sizes are available: 185 x 15 and 185 x 16. ”

See also this Pirelli tyre recommendation for 1962.

[Terry_McGrath]

I will remind readers of a previous thread along similar lines

[xk] Pirelli Cinturato

Pirelli have just produced a new batch of the 185Vr16 CA67 Cinturato that is the best tyre for an XK Jaguar. https://www.borrani.com/185vr16-pirelli-cinturato.html I believe they were an option on the XK150, if you could afford them, does anyone know any more about that. Dougal Longstone Tyres– Longstone Tyres South Yorkshire, United Kingdom –Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

and just for the record here are the tyres offered and fitted by Jaguar themselves in the late 1950’s for customers!
I will add the prices as well
XK150
Dunlop whitewall 10 pounds assume set of 4
Dunlop Racing R3 12 pounds ten shillings and sixpence
Avon Turbo Speed 6 pounds
Continental Extra Super Record 28 pounds 10 shillings
Michelin X 4 pounds 2 shillings and sixpence
and the old favorite the topic of this thread
Pirelli Centurata Price not listed

Interestingly this same factory document list Harold Radford conversions and the other day I picked up a october 1958 Jaguar Price List and it lists all the Harold Radford “Countryman” adaptions for the MKVIII and MKIX each noted a Jaguar spec number: J16 A fishing rod container!

prices quoted are then plus purchase tax
terry

PS Pirelli Centurata spelt as per factory document

[Nick_53_XK120_OTS]

this,from Autoweek website " Pirelli to manufacture the Stella Bianca ,“Pirelli’s longest-lived tread pattern The new tires look identical to the original design …The tread pattern and sidewalls are the same. Pirelli’s Fondazione archive has all of the old documents and pictures, which the company used to recreate the classics, including the old logo. The tires are 6x16 inches, on sale in January, prices next month." A little unclear,.,first says bias.,but may be bias look, and may actually be radial,.,but not say that?

For the discussion at hand,anyone able to contact the Pirelli archive on these topics???

[Wiggles (Paul Wigton)]

I have this vague memory, of Pirelli making a tire where one could change the treads, from performance, to winter… using the same carcass: anyone else recall that?

[Bob_K1 (Bob Knijnenburg)]

Terry,

This is an old discussion indeed!
Apart from your (1958?) internal Jaguar memo we’ve been unable to find any other indication that the Pirelli Cintura tyre in size 185 x 16 has been produced prior to (autumn?) 1961.
We also discussed then that the error in the spelling “Cinturata” might indicate that Jaguar may have been in discussion with Pirelli UK about future deliveries. But we can doubt whether Jaguar would make such a big mistake in a formal announcement regarding the availability of these tyres to their agents (and customers).

Bob K.

[Terry_McGrath]

but then again it could be as simple as a typists error on an internal memo advising what extras Jaguar where actually providing to customers!

"But we can doubt whether Jaguar would make such a big mistake in a formal announcement regarding the availability of these tyres "

[Roger_Payne]

Bob,

1000 apologies. When preparing this response/correction to this subject of ORIGINAL XK TYRES, I looked for your XK Gazette published paper (as well as our private correspondence) but couldn’t find it then. I looked up my electronic files under TYRES and couldn’t find, and didn’t have the energy to dig out my old copies of XK Gazette. I have just now found your papers stored under WHEELS - so its all your fault , titling your paper XK WHEELS and TYRES. For those interested, it is a three-part paper published in XK Gazettes, March, April and May 2018. If anyone wants copies of this three part paper, I can send if contacted direct, as indeed I am sure Bob can.

But it 100% correctly, notes that only DUNLOP branded cross-ply tyres were offered new on all XK120, 140 and 150, and NEVER radial ply tyres. But does detail the period availability of aftermarket Michelin X radials in 6.00-16 size, specifically targeted as XK replacement tyres. It also acknowledges that Pirelli radial tyres were made in the 1950s, but not in aftermarket XK suitable size until 1960 onwards.

I still say - if anyone has PROOF to the contrary - put up, or shut up.

[Roger_Payne]

Very much in the ‘Put Up or Shut Up’ category Terry McG.
Not sure why you seem to have an ongoing agenda to somehow reinvent XK history, with an apparent desire to somehow justify radial ply tyres as original equipment on your early 1957 XK150, by simply regularly repeating your spurious claims, without providing any believable proof.

1. Do you still think the period photo of your XK150 fitted with AVON Turbospeed Racing tyres, as fitted by the Jaguar competitions department, is proof of original equipment radial tyres on an XK150? Or are you now quiet on this claim, given the September 1958 issue of Motor Sport after a detailed tour of the AVON tyre factory clearly describes the AVON Turbospeed (road tyre) and their developed Turbospeed racing tyre, were in fact both CROSS PLY construction. Not that AVON tyres fitted aftermarket, even by the Jaguar Competitions Department, constitute ‘original equipment’ tyres anyway, that were always DUNLOP cross-ply on XKs.

2. Your claimed 1958 factory original - internal use only - Jaguar memo!. Again, ‘Put up or Shut up’.

If this is the so called Proof that is the best you can come up with supporting original equipment fitment of ‘radial tyres’ to an XK150 (now that your AVON claim is dead), then why do you keep refusing to show a ‘complete copy’ for scrutiny, rather than selective quoting of certain words, and who is to know how selective/accurate your chosen quotes are, or indeed simply showing a ‘cropped’ few words rather than the total memo.

But that’s the problem of course - bad mistake - the cropped words show the glaring error of saying Pirelli Centurata. Sounds to me like someone getting a phone call from Pirelli UK, and not hearing either Cintura or Cintuarto correctly, and definitely not knowing how to spell it, given I suspect little more than forward-planning advise from Pirelli, to someone in Jaguar considering/canvassing future availability of tyres. But of course, you now blame the typist! I guess given your spurious efforts at justifying your radial ply tyre claims, I too would be reluctant to show the entire internal memo (if indeed you have any such thing), as if so, apart from ‘Centurata’ spelling, what else may be exposed. We already have better proof that the Pirelli radial, whether called Cintura or Cinturato, was not made in XK 16in size until 1960 onwards. Sounds to me that Pirelli (UK) may well have delayed any plans (if indeed they had them) to introduce an XK sized radial tyre given no interest from Jaguar as ‘original equipment’ nor ‘optional equipment’; and maybe there is another ‘internal memo’ to that effect.

Jaguar indeed did not finally offer Radial Ply tyres as original equipment until 1963, with a number of safety concerns over safety (handling characteristics and potential for mixing with cross-ply tyres) and suitable speed ratings. Indeed they did issue a warning bulletin (not internal, but widely distributed) about dealers fitting radial tyres for insistent customers. This is all part of the UK tyre Industry and Government Regulations introducing a mandatory requirement to determine the S and H speed rating system (V added later), and for that rating to be visibly marked on the side wall. And also the agreed convention of using metric (185 etc) widths for radial tyres, and also the symbol ‘R’ and ‘Radial’ to be visibly marked on the tyre sidewalls to quickly and easily be differentiated from cross ply tyres in inch width sizes, and no ‘R’ marking of course. These changes were introduced in 1962/3 and were in place before Jaguar ever offered Radial Ply tyres as original equipment (and thus be legally accountable) on any model Jaguar, so well after the last XK150 was built, and indeed also after the E-type was introduced fitted with Dunlop RS5 cross ply tyres still as standard. According to the JDHT records Dunlop SP.41 HR and Pirelli Cintura HS 185R-15 (Radial tyres) became available from May 1963 onwards. And note, the factory records from 1963 were still saying Cintura and not Cinturato

3. It would appear that the JDHT does not appear to have even a copy of your so claimed 1958 Internal Jaguar Memo, let alone of course the original that you claim to have.
   Nor indeed do they seem to have anything at all regarding actual original equipment or optional equipment radial ply tyres of any brand, being offered on any XKs at all.

4. So good luck with coming up with some actual/believable proof re original equipment radial tyres on any XKs at all. Your AVON Turbospeed claims are dead in the water, and your reluctance to show the full copy of your claimed 1958 internal-memo suggests similar fate for your Pirelli claims.

5. The closest, but still not original equipment, claim re XKs getting radial ply tyres, is the claim that ‘some’ XK140 and XK150 delivered new by the French Distributor Charles Delecroix in Paris were fitted at customer special request with Michelin X 6.00-16 radial tyres, which were most definitely then made in the 1950s and readily available aftermarket. But these XKs left the factory and were shipped to France still fitted with Dunlop Roadspeeds, or RS4 or RS5 depending on age, with the Michelin X fitted by Delecroix prior to new car customer delivery. But still no hard evidence of this otherwise ‘believable possibility’ claim, even from the French XK experts.

[John]

excuse me but I meant this for the other thread on “cheap tires” and not this thread on original tyres!

John

[Nick_53_XK120_OTS]

web search for Pirelli Stella Bianca,and select the Pirelli site, ,Pirelli says it is made in bias cross ply but new technology, and in 6,00-16, Pirelli tells of the history of this tire being made into the early 50s, and its use in race cars, then the Stelvio, Mention is made of Pirelli archives that have all the records, This site mentions the tire being fitted to the Jaguar XK120,tho not specific as to factory or after,I will bet Pirelli has records and photos,
Nick

[Roger_Payne]

John,

I keep getting back to the title of this thread - ORIGINAL XK TYRES.
And note the initial posting was re a photo of the tyres on the October 1948 UK Motorshow XK120.
So any discussion regarding radial tyres, and modern reproduction tyres is another topic.

Up to you if you ‘don’t think there is any problem with 215/65-16 tires’
All I have said is the tyre manufacturers, the wheel manufacturers, and the Government Regulators in Australia, USA, UK and Europe, and indeed Japan and Korea as well, say you should not fit 215/65R-16 tyres on a 16" x 5" rim width wheel as is original on (most) XKs on the grounds of safety. ‘Safety’ is not a black and white situation, so its not a case of being 100% unsafe at all times, just that in the overall vehicle fleet, an overall operating conditions, including dare I say tyre and wheel age and condition, the safety concern is these tyres are simply to wide for a 5" rim, and thus run the risk of breaking the bead seal/seat causing deflation, or indeed tyre can actually roll off the rim. The chances of that happening in your particular case, who knows. But in Australia at least, fitting 215/65R-16 tyres onto an XK 16’x5" rim makes the car un-roadworthy, and subject to deregistration/prosecution. Maybe that’s not the case wherever you live, you need to check with your local authorities.

The LINK you provided, takes me to the MWS site, where they are offering non-authentic 16" x 6" wide wire wheels. This shifts the problem. 215/65R-16" tyres are an acceptable fitment onto 16" x 6" rims, but I am afraid 16" x 6" rims are not a legal fitment (in Australia at least) on any XK, unless you have obtained a recognised/accredited Engineers certification, that approves this safety related wheel-width modification, and its XK installation/useage. Such Engineers need multi-million $ professional indemnity insurance, so if something goes wrong with the modified vehicle - the Certifying Engineer gets sued, and not the Registration Authority that allowed the modified car to remain registered and thus legally used on public roads. But again, I have no idea what your local situation is regarding wheel-width modifications.

But if the interest is in the relative merits of modern replacement tyres, for use on XKs, that’s a separate topic with a lot of interest, but not under this ORIGINAL XK TYRES heading. And we would be in all sorts of trouble if there wasn’t a source of new tyres, to legally fit onto our XKs, allowing ongoing safe usage.

I for one would love it if Firestone recommenced making their 185R-16 CAVALLINO radial tyre, which I personally found to be an all-round superb tyre; but others will also have their favourites.

[Terry_McGrath]

what were the original fitment tyres on an XK120?

some may recall some pics I posted of 660011 on the other thread [xk] Pirelli Cinturato showing two Goodyear tyres on the right hand side of this car probably discounting that one Dunlop was damaged in transit!

Amazingly I have found this newspaper clipping of the same car with a Goodyear official photo noting that Goodyear Super Cushion tyres as original fitment!!!

“I am sure Tyres were not subject to local taxes, and certainly not an Imported GOODYEAR tyre would not have been exempt on pro-British import/tax regime – the exemptions were only for certain locally make-able accessories. But there is something interesting re this GOODYEAR tyre fitment – maybe factory original DUNLOP was damaged in transit, and this was part of a local on-arrival repair, that has also required the wheel to be repainted, and over the top of the balance weights. Whatever – but certainly not an ex-factory tyre fitment.”