Radial versus crossply tyres

[Richard Coney]

I have radial tyres on my D25 coupe, Generals on the front and BF Goodrich on the rear, P225/75R15 at each end. There's plenty of wear left on them. The steering, especially at low speed is very heavy. I've been told that fitting crossplys, as were originally supplied, would improve matters considerably and outweigh any "wandering" tendencies the car might develop as a result. I've been offered some Coker whitewalls from a rolling chassis someone is parting out, which I hope will be much cheaper than buying new. If they are offered to me in due course what size should I be looking for ideally? Should this "lighten" the steering?

[desoto1939]

If you are going to put on the original bias-ply tires then you need to put all 4 bias-ply on the car. You do not want to have a mixture of bias and radials.

You will have a very serious handleing issue. In 1949 most US cars went to 15 inch tires and 48 and back had 16 inch tires. On my 39 Desoto I use 600x16.

Rich

Desoto1939@aol.com

[Richard Coney]

Quite correct. Sorry if I implied I would only change the fronts. I would only fit a set of four. I also hope to change from the 1" whitewalls to a full whitewall, which is more in keeping with my car.

I have a silly question. Are what I referred to as 'crossply' tyres the same as the 'bias-ply tryes you mentioned?

[jimainnj]

I would be concerned about the age and condition of tires from a parting out rolling chassis. The last time I put on a used tire it blew out the following day.

[Richard Coney]

Good advice! I'll have to see them before I make up my mind. However, being Coker, they should not be too elderly. I gather the correct size should be 6.70x15 to match the originals, as my D25 is effectively a P15.

[RobertKB]

I have a silly question. Are what I referred to as 'crossply' tyres the same as the 'bias-ply tryes you mentioned?

Yes, crossply and bias-ply are the same thing. If your rims are 15", tire size for your car would be 670-15. Go to Coker tire http://www.cokertire.com/ and where it says Search Tires by Vehicle put in your information and it will tell you the size needed. I have bias on all my old cars and they do tend to wander a bit more than with radials but I like the look of them better. If the front end is in decent shape and the tires are good, the steering should be lighter but tend to wander a bit more than at present.

[greg g]

I have radials on my P15, and they are hard to turn with the vehicle at rest, but the difference in the way they drive, handle, and brake offsets that inconvenience. So I guess how you drive your car enters into the equation. I do a lot of highway driving. last forray was a 975 mile vacation trip.

One thing to look for is if the tires have a date code on them. It has been brought out in the media here that even brand new tires from the tire shop had been sitting in warehouses and on shelves for 6 years or more, and as such shouldn't be mounted and used. If they don't have a code, chances are they are older than 6 years, and probably should be avoided.

Generally narrow white walls are made with a application that is bonded to the tire with heat and pressure from the bead out. The black rubber from the inside of the white ring back to the bead is a thin veneer over the white which can be abraded off to expose the white down to the rim. So if you decide against the Cokers you might be able to make wide whites from your current tires.

[claybill]

in a previous discussion..radials on cars without pwer steering should be run at 35 lbs.

some cokers are made in mexico..others in penna.

do not mix radials and bias.

up front..215x75.15's.....225's are a bit large..(not bad for rears though)

bill

[Normspeed]

It's difficult if not impossible to match the bias tire look with the radials, but I sure like the way my car handles with the radials. Much more predictable particularly on the highway. Also I don't find it all that hard to turn that big diameter steering wheel, even when parallel parking. I run Michelin 15" radials in place of my original 6.70 X 15 bias plies.

[47heaven]

I went to radials (not by choice), but looking back I'm sure glad I did. Since I like to drive my car a lot, I was wearing out the bias ply whitewalls fast. I assume that bias ply whitewalls are more for show and not the everyday driver. As already mentioned, you will sure appreciate how well they handle on the highway and the fact that you don't get thrown around everytime you drive over a crevice on the freeway. At first, I kinda felt that the radials gave my car more of a custom look, which I didn't want, but now that I have the steel whitewall rings on there the tires look more to original specs.

[BobT-47P15]

I ran radials for a time several years ago. They were a used set.

Replaced them with a brand new set of 2.15-15 Firestone reproductions

from Coker. Good tires, but you sure notice the loose steering and all the

ruts in the pavement now.

Granted, the radials are harder to turn at stop or very low speed. But the

highway driving difference was notable. Have been considering going back

to radials, even tho the bias plys are still like new. I do hate to lose the wide

whitewall look, as your average radial has a narrow white stripe. And those

are getting harder to find nowadays.

There are some wide whitewall radials now, but they are sorta pricey.

About $188 each before tax and shipping.

Borrowed this page from their website. Link to their ad......http://www.dbtires.com/tires.html

Edited October 17, 2009 by BobT-47P15

[Robin (UK)]

I have experienced exactly the opposite.

I changed from radials to bias ply on my (ex) coupe, I now have bias plys on my 'vert and I wouldn't dream of changing back.

I do most of my miles in the city - so that means slow speed (Richard also lives in London, so I guess he'll be in the same situation).

Bias plys mean lighter steering at those slow speeds.

Handling at higher speeds is absolutely fine.

I believe that bias plys will highlight any deficiencies in the front end set-up but a tight and correct front end with bias plys is, in my experience, not a problem.

Or maybe it's just that our roads are better!...

NOT!

[paulbone]

Glad you added the NOT Robin, the roads are shocking around here and my old Plymouth bounces all over the place in all the ruts and pot holes.

To throw my hat into the arena for Richard. I use wide white radials (Coker) on my wifes 58 Chevy, and they are fantastic in all road conditions - front end is set up correctly.

On a good road the biasplys on the Plymouth (P7) are great, on a bad road not so great.

On the D24 coupe with Firestone biasplys same story as the P7.

Now on the wifes 52 Kaiser they are just straight radials and an absolute pig to steer at really slow speeds, but much better on the road at speed.

Bottom line is, if you want appearence and good all round preformance, go with WW radials.

If you dont mind the odd bump and wander, but easier slow speed steering go with the biasplys.

If you want to keep the advantage of higher speed handling but slow speed heavy steering stick with what you've got.

Having said all that, if you chose not to have the tyres you've been offered, I'll take em for my next project - i'm near Harrow.

I did see you the other day on the Uxbridge Road - looking good.

[BobT-47P15]

Part of my problem is I need to have the steering gear box rebuilt....and maybe

some other things done. Have some play in my steering. Not too bad around

town, but a bit of a nuisance on the road. Gotta keep right on top of things, both

hands on the wheel on curvy roads. I don't go on many long trips, but even the 50

or so miles we drove a couple weekends ago was a bit of a hassle.

The radial tires do hide that sloppiness of steering while on the highway......

[Andydodge]

Onmy 1941 P11 coupe I changed the Republic brand 6.00x16 crossplies on stock 4x16 rims, how old they were I have no idea, maybe 10yrs(?) to 15x6/7 rims with Coker Classic radials.......best thing I have done, steering maybe a little heavier at low speeds, tho' to be honest I haven't really noticed but what I have noticed is that it doesn't wander, follow ruts in the road, etc......it drives almost like a normal car with the radials.........wouldn't run crossplies again, tho' everone should be made to drive a car with crossplies at least once to realise what an advancement radial tyres are.........my 2.5 cents Aust worth(actually has increased in value lately against the greenback, lol).....andyd