1968 Wheel and Tire Sizing Question

[68 Ragtop]

Hi all,

I've got a 68 which is kindof one of those years that gets missed by a lot of the threads. Most guys seem to have the 70-72 era and I want to be sure that I get the right combo of wheels and tires.

right now I have 14" wheels with 225 60's all around. I'm going to buy a set of 15's and I wanted to know what the best combo would be for the 68. I don't want to have to modify the wheel wells to get the tires to fit.

I was thinking about buying a set of 15X8's for the back and 15X7's for the front. I would then like to put either 295/50's or 275/60's on the rear and 245/60's on the front

Does anyone know if the 295's or 275's will actually fit on the rear of a 68? And if they do fit, what wheel did you use and what was the backspacing of that wheel?

In short:
What size rims/backspacing for the rear of a 68?
What size tire for the rear of a 68?
What size rims/backspacing for the front of a 68?
What size tire for the front of a 68?


Thanks in advance for any advice. Hopefully lots of folks will find this type of information useful.


Shawn

[buick64203]

This thread might answer some of your questions...http://www.v8buick.com/showthread.php?t=97563

Contact "Buickbuddy" Dave Shaker. He should have the lowdown on what you need. :TU:

[68 Ragtop]

Ok,

thanks for the tip on the thread. that thread lead me to many others. I found this thread:

http://v8buick.com/showthread.php?t=57677&highlight=backspacing

which proved to have the best empirical data from a 69 rear tire fitting.

The results can be summarized as follows:

275/60 with 15X8 wheels with 4.5" of backspacing do not fit on the 68 /69 without trimming the inside wheel well.

If you increase the backspacing to 5" - 5.5" it allows the tire to clear the outside without putting it into the frame on the inside. On the 5.5" backspacing he ended up using 11/32" of spacer because the inside frame clearance was too tight. the "adjusted" backspacing with the spacer is 5.5" - 11/32" = 5.16" suggesting that a 5" or 5 1/8" backspacing might be ideal on the 68/69.

Biggest/Best Combo for the rear of a 68 / 69 = 15X8 5 BS with 275/60's :beer

If you go with the stock 15X7's then the backspacing would need to be reduced by 1/2" to keep the wheel centered (1/2 the difference between 7' wide and 8" wide). But the tire mfgs don't recommend a 275 on a 7' wide rim so...

Of course all of this depends on what rear end you have and how well centered all of your "parts" are.

If any of this info looks wrong, please let me know. I think I'll go with the following on my order:

275/60/15's on 15X8X5 on the rear
245/60/15's on 15X7X4.5 on the front

Shawn