question on larger tire size?

I am wondering if anyone could explain to me wether it is really worth paying the dealership to reprogram the ECU when switching to a larger tire size? My speedometer is already reading about 3 MPH too fast with my stock 215X70X15's, but my GPS pretty well agrees with the odometer. By going to 225 X75X15's the speedometer should balance out, but what will happen to the odometer? Will it effect waranty longevity? Thanks for any advice?

 

Larger tires in effect slow your odometer down, so you'd be registering fewer miles than actually traveled. Could also result in longer warranty coverage due to inaccurate mileage showing

And for the price of the dealer reprogram you could pick up a scan gauge or an ultra gauge. I recommend scan gauge. Both are user programmable and will show you a variety of different parameters of your liking.

 

Why is your speedometer reading 3mph over if your running stock tires?

 

Most, if not all 2nd gen Tacoma speedometers are off to the fast side a few mph's. If my speedo is reading 65 I am really traveling at 62...this is confirmed by gps and the police traps that display "your speed is" there is a thread on the subject. The consensus was that going up a size (eg; 265/75/16 or 265/70/17) on an other wise stock truck would yield accurate speedo readings and slow your odometer not sure on the respective % changes, but there are calculations you can do to figure it out.

Type "speedo" or "speedo accuracy" into the search bar, lots of reading on the subject.

I think that those searches will answer the op's ?