Does anyone know how much of a speedometer error one would get by going to a 185 x 70 profile tire instead of the stock 185 x 65 on the 2002 Focus. Thanks

just do some simple math, there is a 20 cm difference in the diameter, so you can figure it out. I don't feel like doing it.

There's online programs to do it for you like try this one(may have to copy and paste) http://www.miata.net/garage/tirecalc.html looking at about a 3% error ie. @ 60mph on the speedo you're actually going 61.8mph!Hope this helps!

i dont think there is enough to worry about 1-2mph either way the popo wont say anything.

Thanks guys. I was also wondering if wheel well clearance could be a problem in snow with the larger tire. Any experience with this?

as long as you are on 15 inch rims, you will be fine.

Speedos are normally underclocked by 5-10% anyway so I don't think you have anything to worry about.