rules for tires

[sparky65]

I am getting ready to put tires on my car and i wondered about the judgeing rules for tires. My original tires would be 6.95x14 bias ply tires. I see coker sells a reproduction bias ply but I was wondering if it would be acceptable use a modern radial of the same size. Ive been told the Firestone FR380 tire looks very close.

My two reasons for doing this would be cost and drive-ability. I am too young to know how a car drives with bias ply tires but I keep reading it is awful.

[Shop Rat]

You need to spend the money and get a set of proper bias ply tires if you intend to show the car at AACA Meets. Otherwise you lose all your points for tires which can include the spare if it is also incorrect. It will be as if the car is sitting there on blocks.

There are no safety/drivability exceptions to this. If radials were not a factory option for the year/make/model you have then they are wrong and will be deducted for.

[sparky65]

I should have read the rules before I asked. I forgot they were online. I guess it does seem pretty clear I need to spend the money on tires.

[Shop Rat]

Yeah, I think it would be a good idea. I know of quite a few, that have the ability to do so, that have show tires and driving tires. Saves the wear and tear on the show tires. But be careful, there are issues with putting radials on rims that were never meant to have them.

The expert on tires Eric/Rick Marsh. He teaches the tire CJE class and really knows his stuff.

[DamnTheTorpedo]

Sparky65, it's good to see someone on the forum who is too young to have driven on bias ply tires. Shop Rat's suggestion about having two sets of tires is a good one.

That said, the horror stories you have heard about bias ply tires are greatly exagerated. I have bias ply tires on my antiques and have driven thousands of miles on them. The only time they are a problem is on uneven pavement, or when driving accross the Mackinac Bridge

[Restorer32]

Bias ply tires won't drive awfully. They will drive like the car did when new.

[5219]

"they drive like the car did when it was new"

Well said.

I have bias ply on both of my antiques. On one I changed from radial back to bias ply.

In addition to driving different, they also don't look right on older cars. IMHO, cars with radials sit differently. Anything before about 1970 just doesn't look right with radial tires

[Ron Green]

A also have had no issues using bias tires. Playing around with the pressure will generally get then tracking pretty well. Bias tires that wander get the blame for many worn suspension parts and alignment problems.

[sparky65]

Getting a second set of wheels sounds like a good idea. I never heard of issues putting radials on these rims. The current tires I have are radials and they seem fine but I never drove the car very far after I got it so I have no idea.

[ted sweet]

i have had radials are the stock rims on 66 mustang for over 15 yrs and 35k miles. no problems

[Siegfried]

I learned to drive on bias ply tires. Back in '66 the only cars I saw with radials were Europeans. Mostly MG's, TR’s, Porsches, VW's, etc. BP tires are actually pretty decent. The only problem I ever had with them was they tried to flow ruts in the road, and they got squirrelly on metal grate bridges. In Lancaster Co., Pa. the ruts in the road were from the Amish buggies.fficeffice" />>>
Back in the original days of the Hershey, Pa. hill climb event a local central Pa. driver set a course record in his class driving an early '60tys Corvette on B.P. tires. I'm not 100% positive, but I think his record still stands. >>
The way I see it is that radials are overly hyped up for older cars, and they do cause problems on cars not designed for them.>>
>>

[Restorer32]

Isn't it amazing how those Amish buggies damage the roads?

[Vila]

Hey the Amish buggies were around a long time before we even had any roads other than dirt, so I am not going to complain about them.

It was those "darned" studded snow tires that used to be legal in PA that did a lot of damage to the roads.

I agree with Restorer32, the car will drive like it did when new.

Radial tires won't solve tracking issues on bad roads, my 2002 BMW Z3 with original sized wide radials is all over the road when I drive on roads used heavily by trucks with the ruts in the road, even in the right lane of the PA Turnpike which isn't that bad.

I have the option of bias or radials on my TR4 when I finish the restoration, and am going with Dunlop bias tires since they still come in the exact size and tread pattern originally supplied by Triumph. Michelin X radials were an option, but they are not available in the original size. You can only get Michelin XZX radials in 165-15 now days, the size is correct but that tread pattern didn't come out until the early 70s.

Vila
1933 Chevrolet
1962 Triumph TR4
1984 BMW 633 CSi

[MarrsCars]

Can someone clarify what are the potential issues with radials used on rims meant for bias ply?

[MCHinson]

You may want to read this article:

http://www.sema.org/files/attachment...el-Fitment.pdf

[MarrsCars]

Very useful, thank you. I will make a habit of checking for stress fractures. How can I find out if my '62 was fitted originally with Bias or Radials? My data card shows it came only with "Dunlop 7.25.13" but no mention otherwise. I know MB was advanced for their time in many ways, for example I don't need to use lead fuel additives because they already used hardened steel in the sleeves, so I'd be curious to know if it came with radials or alternatively if the wheels would be built to a tougher standard as a matter of course.

[novaman]

Just a side note, if you're using radials on what was bias-ply originally and you keep losing hubcaps, put bias back on and your hubcaps will stay on.

[Dick380185]

"they drive like the car did when it was new"

Well said.

I have bias ply on both of my antiques. On one I changed from radial back to bias ply.

In addition to driving different, they also don't look right on older cars. IMHO, cars with radials sit differently. Anything before about 1970 just doesn't look right with radial tires

I agree. I'm sure many people can't see the difference in appearance, but I can. The cars sit quite a bit lower on radial tires (which have a lower profile) and do not look quite right.

I've always enjoyed the way good bias tires rode and handled on my '46 and '63 Oldsmobiles (with the exception of driving on grooved concrete. )

[Bob Stein]

Check all of the available factory documentation for your Mustang, STARTING with the owner's manual. I recently got a 1967 Cougar with 185R14 whitewalls that were nearly new. Everyone told me that Ford did not start using radials until 68, and even then the Cougar used FR60-14s. There was no mention of radials at all in the sales literature or shop manuals. But last night I finally pulled the original owner's manual (1/67 printing) out of the glovebox and in the specifications section it listed 185R14 radials as an option under tires! When all else fails, read the manual. (And yes, I sent scans of the docs to Rick Marsh so he'll have a new tidbit.)

UPDATE - There is no joy in Mudville... Gor a reply from Rick - the documentation I found lists the radials only for the GT, so only bias ply will be accepted for my XR-7. Unless I find something factory that applies the radial availability across the Cougar lineup. The search goes on!