Ok I got some new tires last Friday, I had gotten them staggard so there would be no rubbing on the front tires when making turns.

Fronts - 245/45/17 and the Rear - 275/40/17's ( Nexens ( http://www.answers.com/topic/nexen-7000 ) - Are identical to Michelin Pilot's ) which I found out that they are being sued for copyright infringement as I was told and was like uhhhh thats not good, but anyways.

I have looked at some of the online tire calculator's and not sure if my speedometer will be off any or not?

Didnt know if it would be off by 5miles over or 5miles under?

 

know anybody with a garmin, tom-tom, or other GPS device?

 

I wish I did, any other ideas?

 

get some string and go around the outside of the wheel and if it measures out to 26" then you are good to go. 26" is same as stock which a 275/40 should measure out to.

 

should be showing the correct speed

 

Thats what I am thinking being that I didnt change much with the tires, but damn when I hit the gas I can really feel the pickup now...gotta love fresh tread's!

 

245/45/17 and 275/40/17 are almost the exact same size. Its why us guys rock 275/40/17s on stock and 17x9 wheels.