winter tires and the speedo

[Skanky]

does having winter tires make the speedo read differently???

my wife and i were on the highway last night, she was in her protege and me in my MSP. she said her speedo said 125 when mine was reading almost 135 kph???

what gives???

[Turtle of Time]

depends on the tire size and size of the wheel.

[Protege52003]

if you diameter of the tires is different than stock you reading is going to be off!

[Protege52003]

this is pretty good but does not allow you to change the width if the rims if you are using two different size rims!

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

-R