Anybody out there ever hear of a 275/65/15 ? Do they make that combo ? I'm considering going from the 255/60 to something like 275/65 to increase width AND increase tire height to knock down the rpm's a bit as I'm running 4.10's right now and would rather not have to swap gears if possible.

Would this adversely affect handling, make the car more bouncy ? Not looking for drag tires, just radials.

The fronts are 225/70/15 so right now the front tires are actually a touch taller than the backs. Stance wise, I think the taller tire should look fine vs. what is in the front.

Would somebody have a photo of something in the 29" tall range on a 69 ?

Thanks,

Andre

I don't know about a 275/65/15. But the 275/60/15 is 28" and will lower your RPM's by about 150rpm. BFG has a 255/70/15 that is 29". No wider but will drop your RPM's by about 250.

I played with some tires sizes in an RPM calculator and figure it averages roughly a 3.5% difference in RPM per 1" of tire diameter...........

3.31's @ 60 mph, tranny 1/1:
26" = 2566.523 rpm
27" = 2471.467
28" = 2383.2
29" = 2301.021

4.10's @ 60M mph, tranny 1/1:
26" = 3179.077
27" = 3061.333
28" = 2952.0
29" = 2850.207

your best friend when selecting tire sizes:

http://www.miata.net/garage/tirecalc.html

Thanks for the replies, I know how much the increase will drop my revs,. Really looking to confirm what 29" combos are out there and to see if anyone has pics on a 69.

Thanks 1!