# 2002 Toyota Tacoma Speedometer Accuracy **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** tacoma, speedometer, toyota, tires\ **Created:** [May 26, 2009, 2:38pm UTC](https://community.cartalk.com/t/2002-toyota-tacoma-speedometer-accuracy/30999 "2009-05-26T14:38:24Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Fennell](https://avatars.discourse-cdn.com/v4/letter/f/5f9b8f/32.png) [@Fennell](https://community.cartalk.com/u/Fennell)\ **Post date:** [May 26, 2009, 2:38pm UTC](https://community.cartalk.com/t/2002-toyota-tacoma-speedometer-accuracy/30999/1 "2009-05-26T14:38:24Z")
I know how tire sizes and speedometers work, but mine is puzzling me. I have a (used) stock Tacoma with it’s standard R17 tires on it. It’s just a regular truck, no crazy off-road equipment (though it is a 4x4). When my speedometer is steady at 70mph, my gps is steady at 68.5mph. If I’m figuring things out right, my speedometer is actually calibrated for a larger tire size, right? This, even though the R17 are the largest standard size available. I guess my questions are 1) am I right? 2) any way to fix this, and 3) what size tire could I put on to fix it? ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [May 26, 2009, 2:59pm UTC](https://community.cartalk.com/t/2002-toyota-tacoma-speedometer-accuracy/30999/2 "2009-05-26T14:59:26Z")
Speedometers can have a reading error of as much as 5%. That difference between your GPS and the speedometer of 1.5 MPH isn’t something you want to put money into to try to get the numbers to match up. Tester ---
**Author:** ![Fennell](https://avatars.discourse-cdn.com/v4/letter/f/5f9b8f/32.png) [@Fennell](https://community.cartalk.com/u/Fennell)\ **Post date:** [May 26, 2009, 3:02pm UTC](https://community.cartalk.com/t/2002-toyota-tacoma-speedometer-accuracy/30999/3 "2009-05-26T15:02:50Z")
Yeah, I probably won’t spend any money on it. I knew about the 5-10% error, but it’s just seems strange that it’s consistently off by the same amount.