special tool

I would like know, from a tire expert, exactly how much additional circumference a Michelin 275/40/17 has over the stock original equipment 951 tire.
Thanks.

mclarenno9

Exactly which model are talking about here Tool? Stock size is I believe 25" circumference. Look at Tirerack's spec pages for each individual tire to get circumferences...

http://www.tirerack.com/tires/Compar...rk=1&x=27&y=14

special tool

Pilot Sport

lejams

3.14 x Diameter = Circumference

mclarenno9

Well I'm an idiot. Sorry I said circumference and meant diameter. Anyway, Pilot Sport Cups would have an additional 2.2" of circumference over a tire with a diameter of 25". The Pilot Sport PS2 has an additional 1.9" in circumference.

Are you trying to calculate speedo differences between tire sets or what?

special tool

yes, but I need to verify exact numbers. I need accurate numbers on the oem tires also.
Not ps2's just pilot sport.


You guys would be amazed at exactly how these numbers come together at the dragstrip when you figure the speed, datalogged revs, gearing and tire sizes.
I have it to tenths, going over some information I have here - pretty interesting.

mclarenno9

Im going on a diameter of 25.67" from here for the Pilot Sports...

http://cgi.ebay.com/ebaymotors/275-4...QQcmdZViewItem

And an OEM diameter of 24.9", an average from many OEM sized, V-rated tires 205/55/16 and 225/50/16.

Using those numbers you get circumferences of...

Pilot = 80.644683417649992431336055648785 inches
OEM = 78.22565707438585163771982024366 inches

tyro

Calculate here:

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

adrial

If you are really looking for accurate...then tread wear is probably going to play a role.

333pg333

Couldn't you have been a little more exact...lol.