1968 tire size
 

First im a new guy so thanks in advance for your help. I have a 68 conv with the L79, 4 spd, posi. I bought it new in 68 and its been in and out of storage these many years. It has 30K original miles on it.
When I got the car, I put 1968 ...8 1/2 by 15 american s TT on it and later changed the tires to....yeah old size F-70 by 15 and G70 by 15 Goodyear polyglas tires which have lasted until now. While the tread is still good.....the sidewalls look a little sick...since its summer ,its time for new ones...while I have the orginal 68 wheels etc I kind of want to keep the americans.......my question, finally ...It looks like 215 and 225 by 70 tires will fit...wondering about 225, 235, 245 by 60 fitting without rubbing, either on the ralleys or the americans. I am concerned about the tires sticking out too far from the fenders, ie the actual tread width . Anybody with a 68 have any comments....suggestions thanks again BIll

I have (believe it or not) F60 x 15 on my rear. I bought these tires back in 1978. They are on 10 inch rims. These are eqivilent to 235/60/R15. They donot extend past the fender. Originally when Ibought the car it had L60 x 15.

The 225/70/15 is a good all around tire size. I had these on the front of my '70 with no rubbing. I ran 255/70/15 on the rear with no rubbing. These are both on 8" wheels.

BigBlockk

Later.....

My 1968 had, up until a year ago, G70-15 tires. These were mounted on the stock 1968 wheels.

Time to replace your wheel diameter? Unless you're NCRS oriented, it's probably time to start thinking about modern wheel diameters. To get a good selection of tires, you really need to get away from 15 inch wheels. CorvetteFever magazine did an article about wheels/tires a year or so ago. Maybe you can access the article on their website. Actually for performance tires, there are only a few 16 inch tires available. For a good selection of tires, you have to move up to 17 inch wheels.

I chose Wheel Vintiques 17 inch wheel that looks like the standard stock C3 rally wheel. That is "looks like" from a distance of maybe 15 feet. The wheel is all aluminum. Polished to replicate the "beauty rim" and grey powder painted in the center. It has the rally wheel hat. I have mounted 225/50 R17 tires. This tire/wheel combination resulted in a 1/4 inch clearance with the emergency brake bracket on the trailing arm. I switched over to offset trailing arms just to be safe.
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Some of the websites have drawings telling you what the dimensions mean, for example 225/50 R17. After I bought my wheels, I made cardboard templates of the tire cross dimension. With my unmounted wheel on the car, I used my cardboard template to scan and sweep around the wheel rotation looking for interference. The 225/50 R17 looked tight but ok. With only 1/4 inch clearance, I later chickened out and went for the offset trailing arms to get rid of any possible interference problem.

I've got 235/60/15 on front 245/60/15 on rear (all 8" wide rims) no issues with rubbing. See My Corvette Photos for pics. Used to have 245/60/15 on front, no rubbing either.

Have you seen this article:

More Bite for Old Sharks

http://forums.corvetteforum.com/imag...es/cheers2.gif

Hiyas to another '68 owner :seeya

When I replaced my tires, I explored all options. My concerns centered on rubbing, speedometer error, and wandering. I decided to keep the stock 215R70x15 size to eliminate all of those concerns. I could've gone with 225's, but the diameter would have thrown the speedo off and there was a small chance the tires would rub on turns. I was thinking 255R60x15, but there was a chance of rubbing both the front on turns and e-brake besides wandering on grooved roads. So, since mine is a cruiser, I decided to stay stock. Good luck with your decision.

thanks for the info

Thanks.....my concern is that the 68 had smaller wheels and no flares which may impact the size...and then i added the americans to the mix....then g's in the back have a slight rub now with two on board and a full tank if i stick to the 70s i think i will go with 215 in front and 225 in back.....bill

thanks for you thoughts.....

I had read that article before but had forgotten about it thanks for the reminder...photos are a great help and the fact you had them on 8 inch rims...your ride looks just right......very helpful ...bill

Your right the 225 is a little larger.....if i change to the stock rims I might follow you lead.......thnaks for your answer ,,bill

255/60R15 fit on my car at all four corners....w/ factory 15x8 wheels

Current I have 205/15 in the front on 15x4 rims and 275/60R15 drag radials on the back. 15X8 rims

Plan to upgrade to C5 wheels :cool:

I had the same thoughts. Did the same thing.

To put a picture to the description, see my sig.

I have stock 1968 rally wheels. (15x7)

What is the equal size in a red stripe radial tire to replace a F70-15 bias ply tire?

FR70-15, if you can find then through a vintage tire supplier, or 215/70-R15, in a more generic tire.

How tall is a 215/70R-15 on an 8" rim?
 

I'm about needing new front tires and I want to get rid of the 60 series ...

Regarding your question title, I kind of think a 215/70 is a little narrow a tire, for an 8" rim.

On a stock 1968 Chevy Corvette with OEM wheels, I have been able to fit Cooper Cobra Radial GT's in 235/60R15 up front and 245/60R15 in the rear. I felt the rear tire size required relocated the parking brake bracket, while my previous 235 rear tire size did not.

So 235 all around is fine on the factory 7" wheels, no interference, and no modifications needed.

my 68 tires
 

" I have a 68 conv with the L79, 4 spd, posi. I bought it new in 68 and its been in and out of storage these many years. It has 30K original miles on it."


Very impressive! Congratulations!!! Wish I had done that!:cheers:

My 68 tires are 255 60 15 BFGoodrich on AG 15 7 rims. I am happy with the look and ride.

Only a very slight tire rub on front at full steering lock. How often do you turn the steering wheel to either side full steering lock?

Probably need to check your backspace on your American rims vrs the OEM AG rims to see if you would be comparing apples to apples though.

Old thread, but a good one!

So it sounds safe to say that if you don't want any rub, 235 or 245 is the place to be. If you don't mind rub, you can run 255 up front.

I'm curious about the risk of deflection on the tires causing that little bit of rub to become a lot of rub. I also noticed the tire the closest at about 2/3 full wheel turn, not at full lock. I wonder what anyone else has to say on this all though! I suppose I could just try and put a 245 up front and see for myself if it rubs though. I may if time allows :)

How constant is tire circumference/shape? Wouldn't deflection potentially cause minor deformation that could take that little bit of rub to a lot of rub? I know tire deflection and deformation is a concern with the rear park brake bracket, hence even if there's a bit of clearance, you want to relocate it ideally.