Max Tire Width for 56-62?

[Bob B.]

Hi all,

Hope everyone had a Merry Christmas! I'm still working on tires for my '57 race car that would have been available in 1966. I have found a set that appears identical to one of the pictures with the raised white letters GOODYEAR on the side and the width looks similar to the pic. Bob Spicer, one of the original drivers, said they used the widest tires they could get their hands on and Goodyear and Firestone suppliers were right there at the track with the latest.

The tires are repro bias ply 600-15's with a tread width of 8.4 inches and a section width of 10.6. With five-leaf rear springs, 684/687 coil springs and Koni shocks set sufficiently stiff, I am hopeful that there won't be fender issues. However, I'm wondering if there might be an issue with the front tires hitting the inside of the front wheel well when turning, or whether the extra width is mostly outward?

Thanks,

Bob

[William C.]

Re: Max Tire Width for 56-62?

That really depends on the wheel configuration and the offset from the true wheel centerline the back of the wheel mounting flange presents relative to the centerline of the rim. There are a myriad of possible combinations especially in the aftermarket wheel area, so a bit more info is required to even consider an answer. I will say I used a set of 7 inch wide Americans on my '58 Corvette "back in the day" and had no problems with F-70 goodyears, but I can't relate that to your situation, other than to say that the width is centered on the outer rim, and the mounting flange relationship to the centerline is the variable. You should be able to measure that and at least know where you are, before shopping for a different sot of wheels or???

[Tom D.]

Re: Max Tire Width for 56-62?

Mr. B: What's the condition of your front fenders now? Any signs of modifications (like I did to my first mid-year)? Perhaps your car will have less fender rubbing due to prior mods.

And were you considering the 5.5 inch wide steel wheels?

[Steven B.]

Re: Max Tire Width for 56-62?

Bob, are you trying to comply with any specific rules, SVRA, HSR, SCCA, FIA, etc? Which time period/year(s)? Each of these sanctioning bodies have/had wheel and tire specs. (max. size allowed).

I believe you asked before how different engine sizes were classed in '57, IIRC:

B	over 5000cc	3500-5000cc
C	3000-5000cc	2700-3500cc
D	2000-3000cc	2000-2700cc
E	1500-2000cc	1600-2000cc
F	1100-1500cc	1300-1600cc
G	750-1100cc	750-1300cc
H	500-750cc	under 750cc

IF you are conforming to SVRA, and most other vintage race organizations, wheels and tires allowed conform to:

Engine:
The correct engine displacement is required. The entrant must, with certainty, disclose the actual engine displacement. Engines must be of the original type; size and design as originally fitted by the manufacturer and mounts must remain in the correct location.
The following modification restrictions apply:
1. An overbore of 1.2mm or .047″ is permitted unless class rules state otherwise. The standard stroke must he retained.
2. Wet sump may not be converted to dry sump unless class rules state otherwise. Any accumulator (Accusump) is permitted.
3. Induction system must be as raced in period. Duel throttle Springs required.
4. Blocks and heads must be of the same material and design as provided by the manufacturer. Modern aftermarket blocks and heads are prohibited unless they are identical to the originals.
Wheels and Tires:
Wheel diameter must be as originally fitted unless permitted in (the Spec Sheets). The standard width may be increased by 1.5″. Any other diameter or width must be a specifically listed option.
All SVRA groups and some individual car classes have specific tire regulations. In most cases tires are restricted by their profile and tread pattern. Tires must be mounted following the manufacturers specification for wheel width. Bodywork may not be modified beyond period specifications to accommodate tires. All Approved tires are listed in the SVRA Tire Regulations.