Are the 5 and 5.5 width pressed steel wheels of XKs and Mk7-9 suitable for tubeless use? I get different opinions from tire sources. I am looking at Cintarato and Michelin X.
The critical parameter is the lack of a safety bead, on older wheels: w/o that, tubeless use can be a little unsafe.
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Is this profile identified by the J or K in the rim ID?
Not sure, but a quick inspection of the wheel will show it: a smooth rim, from drop center to bead = no safety bead.
Given their age, I doubt they have it.
Art,
All these early 16" rims are of the K type and are not suitable for tubeless. So you need at least a J type of rim or an even more modern version. There are some 15" Jaguar wheels that may qualify, but the choice for smaller wheels is up to you.
Bob K.
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Hi Art,
This topic has been discussed many times and a search on this site will turn up many threads. A good one is:
The conclusion reached (by some of us) was that Jaguar offered tubeless tires on the MK VIIM using the 5 1/2" K profile Dunlop rim design, the same rim used on the later XK-120 and later MK VII (original, not the M). Therefore, if that rim was safe for the 4000 lb. MK VIIM, it was safe for the 3000 lb. XK-120.
I have run tubeless radials on my two MK IX’s for 20 and 16 years respectively,
and for one year on my XK-120FHC, no problems of any kind. I have tube type tires on my 54 MK VII and will be changing them over to tubeless in the near future. My brother has run tubeless radials on his XK-120 DHC since 2011with no problem.
It’s a personal choice, of course, and rim condition is key, they must be in good shape without rust on the stem area or bead area.
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Tis true, that one can run tubeless on older tube-type wheels, and be OK, in normal use.
It’s at high stress levels (hard cornering) where it can be less than safe, so that’s the caution.
The issue is what might happen if the tire pressure should drop unawares. The tire pressure is what forces the bead against the rim. The safety bead is just that, a safety backup. Without the safety bead to physically retain the tire bead, should the pressure drop below some threshold, lateral forces, like turning a corner or a high speed sweeper, would force the tire bead away from the rim. This would result in immediate, potentially catastrophic, complete air loss from the tire. The safety bead prevents that. Since road hazards and slow leaks occur with some regularity, simply knowing that the pressure was good 50 miles ago might not be enough. So my answer is, so long as you accept the risk of this type of failure, including the possibility that you pop a tire, cross the center line and center punch a van load of lawyers kids, these rims are suitable for tubeless tires, ie: the tire bead will hold air, so long as there is enough of it.
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That made me snort, out loud!
Your points are valid, and is why, on a streeter, I’d be cautious. I always thought one could weld on a bead, then trim it up on a lathe, but that would require a lot of work.
On the other end of the spectrum, Formula Vees pretty much all use older, non-safety beaded rims, tubelessly, at 10 to 20 psi, and I never saw a tire peel off on them.
Go figger!
Yes sir. Formula Vee is a series that retains the traditional road racing amateur status of skinny tires and fat drivers (I’M JUST KIDDING!) The cars are also very light, so the forces are low. And I have never seen a van load of lawyer’s kids in the gravel pit at any racetrack I have driven on. Usually it’s just their girlfriends or wife #3.
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Naaaw: FV drivers usually only have one marriage. It’s the guys with megabuck Trans Am cars, or Formula Atlantics that have 3…
True dat.
I used to frequent an online forum for a lower tier formula car series where there would always be a youngster coming up from karts who absolutely knew they could win races in the top tier, if they could only afford the significant expenses of racing. “How can I get someone to pay for my racing?” they would plead. My standard response was “Marry a surgeon. If you REALLY want to race, don’t be particular about gender.” One day, an actual surgeon (Vitreoretinal) chimed in, “That’s ridiculous! Surgeons are FAR too self centered to pay for someone else’s hobby!”
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Art,
The notion of tubeless tires rolling off XK Dunlop rims returns.
For normal driving for us geezers who drive these cars, a modern tubeless radial is the best choice. It is highly unlikely that you will ever have a problem with one that is installed on a good clean rim with a good smooth and painted interior, rust free sealing bead surfaces and stem hole. I have been running Goodyear Eagle LS2 tires since 2011 and have about 20K miles on them since then and have not had a single problem with them. The discussion of them goes back to that time on this forum. You really want to take advantage of the improvements in tire technology and manufacturing for the best ride you can get as well as safety.
No, the 5K or 5 1/2 K Dunlop profile rims do not have a safety bead. This idea came later and will help to keep the tire on the rim for a while when driving a flat tire. A sudden loss of air pressure is a catastrophic event, such as driving over a foreign object or a collision. It doesn’t just happen for no reason. If you are unfortunate enough to have the sudden air loss, the fact that your tire has a tube or not does not matter. The rim without a safety bead will act the same. The argument seems to be more about the lack of a safety bead than tube or no tube.
Here’s another opinion about them worth reading from an MGA guy with the same situation.
http://mgaguru.com/mgtech/wheels/wl106.htm
So if you are just touring with your XK, rest easy. If you a running a JCNA slalom, same thing. Low speed, closed course, and yes, hard cornering. Your skinny tires will break away or you will break an axle before your tires pop off. We have had many stock XK’s and E-types through the years compete in JANE slaloms with no tire failures.
If you want to go racing, it’s a whole different ball game.
BTW, for the belt and suspenders type of guy, you can even get the Goodyear LS2 tires with the run flat option. Of course they are three times the price of the regular tire but they will get you safely home if you are less than 50 miles from your house. Then you have to throw them away. Just kidding.
So, if you are running wire wheels (same 5K profile), yes I would run a tube although Dayton offers sealed spokes. Steel disc wheels, cleaned, de-rusted and smoothed up at the sealing surfaces, are fine for tubeless tires. I wouldn’t recommend that you go out and compete in a drifting contest though, nor would I recommend that you do it in an XK for that matter. 
John Brady
678462
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These wheels have been powder coated so they are still very clean and smooth. The choice of tires is a bit tricky with the minimal clearance on the rear axle with spats. Modern tires are often a bit wider for the same nominal tread size. The round pins on the fenders that hold the spats reduce the clearance to the wheel by a good bit. W/O them I would have a greater range of size and modern rubber probably would be advantageous.
Greetings All,
My concern at least on a car the size and weight of a MKVII/VIII or IX, a radial has obviously different characteristics than a standard bias ply.
The original suspension, being designed for non-radials is now seeing a different set of stresses than it was designed for and that may or may not manifest in a failure mode the car’s components was not designed.
Driven at the pace and distances these cars are now, these days, no harm will come to suspension bits by the use of radials.
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Hi Bob,
As you have probably witnessed, I actively use my two MK IX’s (59 and 61) as much as possible and often take them on fairly long trips, driving them like normal everyday cars. I have twenty years of driving my 61 since full restoration, on radial tires, and put 2300 miles on it last year. It’s on its third set of wide whitewall radials from Diamondback Classics. I am regularly in the outside lane and often get caught in heavy rain, not by choice, since beyond our control. Last year I joined a group of fellow enthusiasts on a 350 mile drive to the Simeone Museum in Philadelphia (under the auspices of Mike Eck, thanks again!) mostly in driving rain. I am running adjustable Spax shocks on that car, and it handles very predictably and precisely, once you get used to the body roll. I’m sure you have seen videos of the big Marks running at Goodwood each year, looking like they are about to roll over on the turns. The suspension works great.
I have driven my 59 for 16 years since full restoration on also on Diamondback Classic radials. I have Gaz shocks on this car and they work just as well as the Spax. In 2007 I competed in the JANE Drag Nite at New England Dragway with this car, a bracket racing event, and won it. I consistently ran around 17.5 second quarters, which is the key to winning a bracket racing event, as well as reaction time. I drove 80 mile each way to and from the track.
Over the last 19 years I have attended the British Invasion in Stowe, VT, about 240 miles each way from my home. I have alternated which car I have taken and, along with others, still plan to drive up this year, even though the event has been cancelled. We usually take a drive up and over the mountain, which is quite an experience as it has some pretty challenging areas. The suspension is well exercised, believe me.
My 54 MK VII, my first car, purchased in 1967, has bias ply tires. I have been driving it for 53 years, on and off, as life has allowed. It has standard Girling shocks that I bought NOS back in the day. Compared to the radials it rides hard and has a different feel, the manual steering and stiff sidewalls being the difference of course. Apples and oranges.
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Greetings All/ Mr. Brady,
First off…is Sturbridge happening?
The bias plays have a harsher ride?
Are you running conventional suspension bushings or something urethane?
Yeah, the body roll the first time was really a concern, but it is repeatable and pretty consistent.
BTW…found a “CORRECT” Standard 20HP Flathead, life is good.
A little word of caution with regard to steel (disc) wheels. I have witnessed a few cars recently suffer failures with older steel wheels - a tuned Morris Minor, and two Riley RMs. The Minor was producing around 100-110bhp, was on 13" rims with modern compound tyres giving more grip than original. Both Rileys had significantly less power, on 16" rims with again, modern tyre rubber. The Minor was often driven hard, the Rileys just gentle touring. In all three cases, fatigue fractures formed around the wheel nut holes between adjacent wheel nuts. The Minor had severe cracking on three wheels and the Rileys had one and two each. In all cases the wheels were scrapped as the metal was judged to have been worked too hard over the years to risk welded repairs.
These were original 1950s (Riley) and 1960s (Minor) rims. It was reckoned that the failures had occurred due to the lateral forces when cornering being exaggerated by sticky modern rubber - although the Riley fitments were all taxi tyres, being all you can get now in those sizes. However, a 16" rim will apply a lot more lateral strain on the hub plate than a 13".
I would never consider performance driving on steel rims that are 60yrs old with modern rubber. It’s more than likely that this thread relates to modern repro wheels, which should be fine - just thought I’d highlight the risks with the old parts.
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A common failure mode on TR2/3/4 steel wheels, too.
Oddly enough, beyond those, I’ve never seen that kind of fracture on any other pressed steel wheel.
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