Is anyone running 245/75-16 tires?

[skategoat]

The online tire size calculators tell me there is only a .-3.5mm difference in diameter from a stock 265 70 16, yet a tire guy I talked to tells me it's a bigger difference and doesn't recommend the change. Not sure who to believe.

 

[skategoat]

No typo.

I'm talking about 245 75 16 instead of 265 70 16.

I think I may know the source of the confusion.

http://www.miata.net/garage/tirecalc.html shows the circumference difference as 1.5 inches. That's the size difference the tire shop referred to - 1.5 inches. Is that a lot?

Revolutions/mile is 662 (the 265) vs. 659 (for the 245). That translates to .5% speedometer error. Big deal.

Or is my math all wrong?

 

[Kmvreter]

Sizes...

The 245 75 16 design diameter is 30.47". The 265 70 16 design diameter is 30.63". A 0.52% decrease. I was planning on investigating getting that narrower tire for the next set of winter tires but I have to run out the Dunflops first.

 

[skategoat]

The guy at Steelcase is telling me not to do it. He says there is a big difference is size. I don't see how .5% is a big difference. You would get .5% speedo error between new and old tires.

I'll let you know what happens. I'm going to call around.

 

[Kmvreter]

Fit...

They will fit. You will have a slightly narrower tread (better in snow?) and more sidewall (possibly softer ride). Shop around for someone more knowledgeable. If you get a tire with a deeper tread then it might even make up the diameter difference.

 

[skategoat]

I called Kipling Tire in Etobicoke. Right away, the guy recommended 245 75 16. Suggested BF Goodrich Winter Slaloms at $145 each installed. Good price, nice guy and close to home. I'm headed there this week.