Regarding use of radial tires on older rims

[blucarsdn]

I think the real issue about radial tires vs bias ply on old rims is the rim width.

The majority of pre 1950 wheels will have a rim width of 4.5 inches, and in some cases 5." for the larger cars... Buick, Cad, Chrysler, etc..

Coker Tire's catalog clearly lists the rim width recommended for just about any tire they sell...

Example; The use of P215/75R15 tires, which are recommended to be on 5.5-7.5" rim, on a 4.5" rim could be an invitation for trouble because the sidewall is pinched in, which causes the tread to have minimal contact with the road surface.

I have used radial tires on just about every car and pickup that I have had since 1965... I replaced the wheels on my '65 Chevy prior to getting a recall letter from GM concerning a safety issue with the wheels.. The tire dealer I purchased the Michelin's from had alerted me to the wheel problem.

The wheel issue had nothing to do with radial tires.. GM had tried to save some money on the wheels, which resulted in wheels that were not up to the maximum GVW's of the vehicles.

I had the rims on the stock 15" Chrysler wheels for my '39 Plym changed to 6.5 to accommodate the P205/65R15 tires I wanted to use...

I wanted the 15" Chrysler wheels so I could use the stock '39 Plymouth dog dish hub caps..

[desoto1939]

Ok Guys, here is the scoop. I called coker tire this morning and spoke to one of their reps. I will not provide the reps name to protect him and also coker from any law suits and liability issues, ok ge the point.

Basically the person stated that they have experience with driving cars from the 60's and has had radila tires onthese cars becasue of the suspension and rack and pinion can support the driving characteristics for radial tires.

His feeling is that the older cars prior to the late 50's and above are not designed to fully support the use of radila tires becasue the suspensions were not designed to run on these type of tires.

Even the AACA does not support the use of radial tires on the cars if they were originally designed for Bias Ply tires. At the AACA Convention back in February there was a discussion at the juding seminar about the safety aspect of radila on the pre war cars. The AACA spokesperson noted that the sidewall design of the radial when going into a turn is not setup to fully support the fron suspension functionality of these cars. Yes you willnot get the wondering that a Bias Ply tire does onthe road but the original Bias Ply is the safest tires for the car to be used at highway speeds.

The person at Coker was also leaning to the same statements but would not officially go on record to protect them and the company.

Also another point is that when your car was originally designed it was design with a specific brand of tire and tread design so the car would steer and track properly. In several states the original tires should alwasy be onthe car to insure that the car handles as it was design and you could officialy have failed your yearly or semi-annual state insepction.

So, all in all, the choice is up to you to install radila or bia ply on your. If you have chnaged the front suspension to a modern drive line line they do with a street rod then go with the radial but if you have the original fron suspension go with the Bias Ply.

I know this is going to stir up the hornets nest for some members but i figured I would at least try to get some answers on this topic.

Rich Hartung

desoto1939@aol.com

[Plymouthy Adams]

so the question remains..can you use a radial on the older car/wheel...lol

[greg g]

Only until the sidewall takes out the rim bead.

[austinsailor]

OK then. Only one question remains.

How can you tell what the rim was made for? Markings? I've never seen any. Shape? I've never noticed a difference - even when I knew their origins.

Can anyone answer that?

[greg g]

Oh I thought you were going to ask tube or tubless????????????????

So you can buy hideously expensive repoped bias ply tires made by some cottage industry in Tennesee, or you can buy thier even more expensive early radial clones.

You get the bias plys and they wander around and follow a rut and throw you off the road, or you can buy thier radials and mount them on your old rims and take your chances on whether the rims will hold up, or you can go and buy new rims and mount Waly world modern radials.

The points have all been made, we know that radials did not become commonly availabe in the US until the late 70's so any rims prior to that were "not designed expressly for radials" But we have testimony that folks have been running radials on their stock rims for miles and years with no problems. As far as suspensions not designed for radials Whats that different Unequal length A arms, over built kingpins as opposed to whimpy ball joints, and parrallel leaf springs are parrallel leaf springs. Our cars weren;t designed for disc brakes either but has anybody found a problem and returned to stock drums??

You pays your money and takes your chances. Caveat Emptor.

[austinsailor]

I think you realized my last post was tongue-in-cheek. My post 15 or so back sums up my opinion.

You do bring up a good point. I mentioned the extra strain on front end parts - which it appears that a later post says Coker agrees with. I hadn't thought about the disk brake aspect. Heck, throw in a t-5 tranny and 75 mph driving, radials and disk brakes - you might twist the a frames right out from under that old mopar with hard braking.

Don, you've got all that. Are your front end parts all still where they should be?!

[Frank Elder]

Or you can buy 5 steel rims to weld your centers to and retain the original look with modern safety.........

[Andydodge]

I have been running radials on my 1940 Dodge since 1973, admittedly using later model steel rims rims,then alloy mags, however the car uses the original style front suspension, albeit a combination of aftermarket cast steel upper arms, original lower arms, adjustable 1" sway bar and rack & pinion steering and 4 wheel vented disc brakes since 1975.........no problems with any of this stuff.

I had forgotten what cross ply or bias ply tyres were like until I bought the 1941 Plymouth Coupe 5 yrs ago..........it came with its original set of standard 16" mopar safety rims and 6.00 x 16 crossply whitewall tyres.

The crossplies were a re-education...........lol.........everyone should be made to drive with a set of these things.........lol.....at least once........anyway 2 yrs ago I replaced the wheels & tyres with the 15" Chromies & Coker Classic radials..............also lowered the car 2"........much better to drive & steers where you want it to go.

I can fully understand people wanting to retain the original wheels & tyres as thats what the cars came with..........just not me tho'..........regards, andyd

[blucarsdn]

The debate regarding the pro's/con's of bias ply vs radial tires can go on for ever... The old car purists will never admit that radial tires just might be safer and more drivable on the older cars.

As I have mentioned in my earlier posting to this topic, I have found that radial tires are far superior for ride, handling and economy..

I have found that there is very little difference between older bias ply/radial wheels... Generally speaking, the 'safety' rims that Chrysler pioneered in 1940 did not start to appear in common use until about 1951 on the heavier GM cars, and then became more common in the early 1970's...

As I have already stated in my 5/3 comments, rim width is the important factor, especially with radial tires... Proper inflation is also very important.. Radial tires are not low pressure tires, if anything they like higher pressures than the 28/30 psi that the manufacture of the car might have recommended.

An additional factor that many people overlook when switching to radials.. The alignment of the front end has to be adjusted for radials..

For over forty years I owned a company that had many vehicles, ranging from cars and trucks, 1/2 ton through 10 wheelers.. I started switching the cars and light trucks to radials in the late '60's, by 1975 or so we had radials on all of the light duty trucks up to F-350.. In about 1978 I got so fed up with tire problems on the heavier trucks that I switched all of them to tubeless radials at a cost of over $1,500. per truck... Switching the heavier trucks to radials eliminated our tire problems just as it had on the lighter vehicles.. As a side bar.. my fleet of trucks ranged from 1959 through 1995, the majority of the lighter pickups/flatbeds were '59/73...