| PM | Quote | Reply | Full Topic |
Owns A Torsen
Joined: Mon Sep 18th, 2017
Posts: 6528
Status:
Offline
Reputation: 
Reputation Points: $user_rep
Yes, tire size CAN affect the speedometer accuracy. My "summer" tires are 235 70R 15 and that throws it off by 3-4 MPH. This is based on the GPS MPH compared to the speedometer. Right now, I have my OEM "winter" wheels and tires installed that are 235 75R 15. Speedometer agrees with the GPS. That being said, there IS a way to adjust for different tire sizes using ForScan software and an ELM 327 OBDII connector. Unfortunately, I don't know how to do that, as I don't bother to change it. I think our member Anthony (SheltonFilms) made a post about that once.
I tried it once and could not get it to stick, just a lack of experience. One of us has to get off our *** and start hacking ECM's and related modules.
____________________
00 XLT 4WD RCSB 3.GO! Jalapeño
01 XLT 2WD RC Steppie 3.0 auto Silver
The future belongs to those who show up.