Radials vs Bias Ply Tyres on a MKV

Hello All,

I’m in a conundrum at present not knowing which tyres to fit to my MKV (standard rims), radials or bias plys? I’m interested in handling and safety especially in the wet?

There is also nearly a $200.00 difference between the two, radials being more expensive.

Cheers,

Tim

For my money, and if the car is regularly driven, hands down, I’d always use radials.

Hi Paul,

Thanks for the response. In what ways are the radials better in your experience? I’ve never driven a car without radials.

Cheers,

Tim

Antique tyre service in West Heidelberg.
I was talking with hm one day and he observed that when people compare they come in with old worn tyres[ which is what has motivated them to spend $$] and tey get a set of ew tyres. And whethe r they are radials or cross ply, they are going to be better than what comes off.
So is the improvement in the aspect of radials or just because they are new
He suspected the later , but is happy to sell radials to customers.
They may be a theoretical advantage on an independent suspension in cornering , but how does this work on a beam axle.?
I would think in regards braking, it might be more to do with the compound making the tyre. It’s a balance between wear, and grip.

1 Like

Compared with crossplies you will be able to take corners much faster on radials and you will find that they are much less likely to deviate when running in a straight line on roads with wiggly surface irregularities.

The only downside of radials on the MkV is that they don’t look quite right and you will probably end up with a lower profile tyre so your MPH/1000 revs will be reduced.

Peter

Hi Ed,

Antique Tyres is where I’m going. They are happy to sell me both though they did say that, "The radials are more responsive in cornering and won’t want to wander.”

I simply want a safer tyre in the event of being caught on a wet road.

Cheers,

Tim

Timothy Fox

Timothy2963@gmail.com

Hello Peter,

Here is the Coker Classic 650R16 3 1/4” radial

And here the Firestone 650-16 4" White Wall

No rude comments about White Walls please!

My goal

Cheers,

Tim
Timothy Fox

Timothy2963@gmail.com

Looks good! Go for it.

Peter

Indeed Peter, faster cornering is always on a MK V owner’s mind. : >)

Very true Ed.

Peter :wink:

And Cecil Vard is on bias plies there in the Monte Carlo Rally!
I went with bias plies on my Mark V only because I was thinking concours where radials would be a deduction.
Radials should improve stopping distance.
The subject comes up often among XK owners and I’ve never heard of anybody on the XK forum that went with radials and regretted it.

And even lately some seem to be able to battle on around a track on cross plys.
The XK List? Some there seem to feel that disc brake conversions will help them on their road going XK 120/140s. Or that straps across core plugs are needed. or even presumably that core plugs can save your block from cracking if frozen.
I’d be interested to see a valid comparison , Same car tested, set of new cross ply and then a set of new radials in a braking test in the same conditions. on one of our old cars.

Hi Ed,

The difference in the cost of the tyres is $200.00 each. I can certainly use that money to do something else on the car if there is no major safety advantage of the radials over the cross-plys. Peter made an interesting point about lower speeds using radials if they have a lower profile. All questions to put to the fellows at Antique Tyres.

Cheers,

Timothy Fox

Dunlop bias ply RS5 tires have been on my Mark V the last 15 years. Two sets at about 5,000 -7,000 miles each (not exactly great mileage). 2nd set is worn out now and Dunlop stopped offering these tires. Loved the cold tire thump when getting going from the garage, tramming effect was vintage feel also (although passengers sometimes were offput by this old school effect), and Dunlop logo on the tire was in the spirit.

Am about to order the Excelsior Stahl Sport Radial. Several factors point this direction. Tread width on the ground will be close to original so steering effort will be similar to factory design (except for higher friction coefficient in modern tire compounds). Rolling circumference comparable to original. DOT rating is reassuring since car is driven in regular traffic, including freeways, and Southern California has few roadside breakdown stopping points in cities these days, this car is not a show car used to a trailer. A lot of vintage tires have no DOT rating, what lack of DOT rating means is unclear to me.

Lots of variables to consider and lots of choices. For me steering effort, rolling circumference, and DOT rating are present leading guides.

Yes, I doubt there is much difference in braking. I still remember being absolutely amazed at the cornering power of Michelin Xs when compared to the crossplies that were at the time the norm.

Peter

***These are the dimensions of the ***

Coker Classic 650R16 3 1/4" radials

  • DOT Approved: Yes

  • Rim Diameter: 16

  • Tread Width: 5.40

  • Section Width (Actual): 6.80

  • Overall Diameter: 29.26

  • Load Index: 99

  • Speed Rating: P

  • Max Load Capacity: 1710@41PSI

  • Recommended Rim Width: 4.00 - 5.00

  • Tube Type or Tubeless: Tube Type
    The dimensions of the Firestone 650-16 4” bias ply’s

  • Tread Width: 5.10

  • Section Width: 7.00

  • Overall Diameter: 29.10

  • Load Index: No

  • Speed Rating: No

  • Max Load Capacity: 1580@32PSI

  • Rim Width: 4.50 - 5.00

  • Tube Type or Tubeless: Tube Type
    Not much difference in the various dimensions.

I was a bit spooked by the comment from Roger about the cross-ply’s “tramming” and cold tyre thumping but more so with the very low mileage you get from the tyres. On my modern car I get 50’000kms out of a set of tyres (country & city driving 50/50). It might be more cost effective in the long run to buy the radials?

Thanks to all,

Timothy Fox

Timothy2963@gmail.com

Yes, I forgot to mention the life of crossplies. I would expect to get 10k miles out of crossplies on these cars but would expect 20k out of radials.

Peter

Timothy
Remember in Australia tyres are only legal for about 10 years… for a reason. I had to change the 16" on my MKVII while they had miles or wear left/ Side walls crack ans compound becomes hard.
Hard compounds wear well , but do’t grip well in the wet.

There are many factors in a a tyre’s performance, Front end alignment, and condition, pressure, ambient air temp, road surface tread pattern , and importantly variation between drivers.
my father was chief testing officer with Olympic tyres. They had a taxi fleet which they used to try and assess new compounds and tread patterns. He said the biggest variation was between drivers. and how they drove.
Flat spots on tyres can vary with Nylon or steel in the trad. Nylon can need to warm up to lose memory of flat spots.

Not quite true Ed.

There is no Federal law on age of tyres, with local state rules different from one state to next.

Not sure where Tim lives, but in many states, including ACT, there is no age law for tyres, just the usual visibility damage and tread depth rules, so a thirty year old tyre with good tread and no obvious sidewall damage is totally legal.

No federal law as there is no sustainable evidence that can justify a ban on tyres based on age alone, despite the tyre retailers hoping/lobbying for age related laws, same way Toyota would like to outlaw cars over 5 years old. Keeps the factory volumes at 100% capacity and maximised profits.

Roger

The tyres on my car at present have good tread depth but the walls are showing signs of fatigue. No doubt they are hard too and I really don’t trust them as they look about 30+ years old. Common sense says that it’s time for new tyres, most likely radials.

Thanks all for the feedback.

Cheers,

Timothy Fox