ixlor8

I am looking for tire size recommendations for a 78 Corvette - Base Model.

Wheels - Factory Corvette 15 x 8 Ralley wheels

Stock tires are 225 70 15

Sixties series will fit too? P255 60 15

I do not want to make fender modifications.

Best to stay with 70's or go with 60's? Which looks better? Rides better? Performs better?

Thanks

Roughrider

P255/60R15 is fine...it's the only Chevy authorized optional tire size for a '78 Vette.

The standard size will probably ride a bit better...the 60 series will handle better as they give more rubber on the pavement, and may take more steering effort. All that assumes all tires are equal which they aren't. That is a general statement.

Which looks better? That's a very subjective thing...whatever looks best to you is what counts.

KapsSA

Without slight front fender modifications the 255s may or may NOT fit. Shaving the lip from nothing to about 3/8" from about 12 O clock to the very front of the opening was GM's solution with the 78/79s but only with the bigger tires. Interference was when turning.
It seems most guys have no problems, tho. Maybe borrow tires from a friend with a Vette to try em.

justaguy10825

I do not have the original rally wheels on anymore but they are still 15x8's... I run 235/60/15 on the front & 275/60/15 on the rear without any modifications or problems....

thegazman

I have a 79 and it came from the factory with the 255/60x15" as an option. 255/60X15" will fit a 1978 without any problems. If you go any wider you need to move the parking brake cable guide to the inside of the trailing arm.

jb78L-82

255/60/15's will fit fine. It depends on the look you want. I have 255/60/15 BF Goodrich Radial T/A's on my 78 with the stock aluminum rims which is the size my car came with. The real issue is that any tire in this size has very poor performance characteristics because they are all S (112MPH Speed rating) or T (118 MPH) rated. There are zero V (speed rated up to 149 MPH) or Z (open rating above 149 MPH) rated tires in this size which is what we all need if you want a great tire. The higher speed rated tires offer much stiffer side wall contruction which greatly aids handling and would allow much higher grip levels from the corvettes suspension. Trying to compare a mid 60's/70's or early 80's vette's handling to cars today is silly since you cannot get a great tire to work in the stock size rims. My 2008 Chrylser 300 Limited V6 has 245/55/18 ZR KDWS tires and has incredible handling with Eibach aftermarket V8 swaybars. It's a sad that we make all these suspension changes to our vettes and really can't take advatage of the modifications unless you change the rims and can find a decent high performance tire. In the mid 90's, BF Goodrich offered a Comp TA ZR in the 255/60/15 size but no longer. I wish some tire manufacturer would market a higher speed rated tire! Is anyone else concerned about this issue?

gbags

78 vette 255 60 15 on chrome rallies no problem

KapsSA

I'm just saying, this is what the factory did on 78/79s to help with clearance with the 255s. Just make sure!

jb78L-82

Would you know why my 78 L-82 F-41 4 spd which came with the 255/60/15's does not have this modification? My tires do not rub with the 255's and never have. The car was built in Oct 77, so thus an early car.

KapsSA

Maybe after getting some complaints about clearance they started grinding away 78 was first year for the 255s from the factory.
All 4 of mine are trimmed.
My friends 76 had no issues with the 255s. Many others don't either.

Roughrider

GM had several suppliers over time for fiberglass body panels. My own theory is that while all vendors supplied panels to meet a minimum specification for clearing the stock 70 series tires, some vendor's panels had clearances that would let 60 series tires clear and some didn't.

True or not I don't know, but it seems a reasonable explanation for why some '77 and earlier cars have no problems with 60 series tires and some do. Starting for the '78 model year the specifications were officially changed to allow 60 series tires.