Switching from 17 to 18 tires - But, that's the point - THERE WILL BE NO CHANGE!!!! Lou Hey, I learn something new every day!

lowrider wrote:

starspangled6.0 wrote: And, if there is any change in the speedometer, you can either get it reprogrammed at a DIFFERENT dealer, or just buy a programmer yourself (usually $250-$300).

But, that's the point - THERE WILL BE NO CHANGE!!!!

Lou

Hey, I learn something new every day!

For Future reference, here's an online tire size calculator, it will show the difference in speedometer error when changing tire sizes.

For the OP, at 60 mph, your speedo will be 0.1 MPH off, can you live with that? I thought so. lol

Honestly, over time your tires wear more than 0.1%. Considering most tread on our trucks is 11/32 of an inch, they can wear away a lot more than that!

Yea, that is true as well, I thought I linked the calculator, well, here it is.

http://www.miata.net/garage/tirecalc.html

Thanks, Folks!! Elvira

I was looking at this post as I am in the process of going from the 17" to 18" wheel. My OEM tire is 245 70 17 and I am going to the upgrade size of 265 65 18. The tire size calculator shows that this will be an increase in the radius change from 15.3 to 15.8 a .5 difference resulting in a difference of 2.1 MPH faster at 60 MPH. This is a 3.5% difference.

Should I be concerned with this?

^^^^To keep the ODs the same, as I indicated in my earlier posts, I went with a 265/60/18. Same OD, 30.5" vs 31.7" with a 265/65/18 tire. I didn't want to effectively change the axle ratio with the bigger tire. For me it was the right thing to do.

Lou

You can get the tire pressure sensor setup changed by the dealer. My stock tires have a factory recommended setting of 80 PSI which would be correct with the maximum payload in the bed of the truck but is way to high by 30 PSI for the truck with less than 500 lbs. in the bed. The Dealer for a nominal charge can reprogram the truck so that the new air pressure is the default and keep you from having to scroll through the error messages every time you start it up.

It is really a pain as it needs to be done any time you change tires for a set with a different load rating.