I'm looking for advice on a tire/wheel combo to supplement my original P255-50 VR 16 Gatorbacks. The car is driven in dry weather, and a ultra high performance tire is desired. Can I use an 18" wheel on this car with no "issues"? If so, then that's my choice. Tire characteristics desired, in this order:

Dry cornering
Dry braking
Low noise
Ride harshness
Treadwear rating
Price
Wet cornering
Wet braking

Thanks in advance

 

In my opinion there is only one tire that meets all of your requirements and that is the Goodyear GS D3. I installed them on my '85 a few years back and couldn't be happier. I only wish they would offer it in a few more popular sizes for the C4's with 16" and the C3's in the 15"... but alas there is more money to be made selling them in the more popular sizes like 20's...



I knew there were few choices in 16's for the '85 so I picked up a set of these wheels from AFS with the correct offset and mounted 255/45-17's on the front and 285/40-17's on the rear. Tire Rack currently has both sizes in stock.

Good luck... GUSTO

 

I bought mine from bonesenterprises off ebay due to recomendations here at CF. I ended up with tires AND wheels 9.5 x 17 and 11 x 17 for under $1200 total. They also sell 18's I recall but for me that was overkill(1984 vette). The wheels were chrome ZR1 and they track perfectly. I read horror storys about not being "true" but mine were A-OK.

 

Your 85 has wheels with a 38mm offset. There are some vendors that have ZR-1 style wheels with the proper offset so that you do not have to use adapters to get a wheel to sit properly in the wheelwell. Try ebay for AFS Wheels or one of the CF supporting vendors for their ZR-1 style wheels.

You can use wheels designed for later C4s with a 56mm offset but you will need 3/4" adapters for proper fit.

As far as tires, a 275/40-17 tire is very close in terms of overall width and diameter when mounted on a 17x9.5" wheel. GS-D3's are excellent tires (Tire Rack has them for around $230 each!) but you should also look at the Kumho Escta MX tire. Much less expensive ($146) and they are very close to the BF Goodrich KD in terms of dry grip. I use them on my 87 for track days and street use and they work great. Also look at the Kumho SPT ($108) for street use.

Treadwear and handling/grip for extreme performance tires are going to be sort of a trade-off. For these types of tires, expect treadwear ratings in the 200-350 range.

As far as 18's go, there are still a wide variety of 17" tires available in 275 or 285/40 that will meet your needs. As the height of the tire sidewall decreases (Asuming the same tire diameter), the stiffness of the sidewall increases leading to a harsher ride. One issue with 18's may be finding and getting a wheel to fit properly given the offset requirement of the early C4.

Some tires will be noisier at highway speeds because of tread designs and compounds used.

 

Are all 4 of your wheels 17 x 9.5, or are your rears 17 x 11?

Strange that many 1988 -1996 Corvettes (except ZR1) used 275/40-17 tires, when the tire DIAMETER calculator determines that a 285/40-17 is an exact rolling rev match (diameter) within .2% of the original P255/50-VR16 Gatorbacks!

Again, strange that the ZR1 used 315/35-17 rears, when the equivalent diameter is the 325/35-17. If I can fit those in the rear wheelhouses without rubbing, mounted on 17 x 11's, then I would do so.

I don't know about yours, but my '85 (maybe the original tires don't help) will "hunt" for any and all ruts in the road. It is twitchy and darts around, almost like it's on rails, whenever there is rutted pavement. Alignment is OK AFAIK. I don't know whether wider tires will exacerbate this problem, or not. Maybe have to modify alignment specs, as well.

Joe

BTW: Leaning heavily toward the Goodyear GS D3's. Many more choices available in 275/40 than in 285/40!