Since I have changed my rims form 15's to the 18's, I have been wondering if my speedo needs to be recalibrated. Scott (t51R) said that if there was a big change in the diameter w/ the tires, than i would need ot have it recalibrated. It looks like the new rims w/ tires are around 1 inch larger than my old setup. I know that I can truly test it by driving 1 mile at 60 mph and seeing if it takes me 1 min. (i plan on doing thsi tom.), but i was just seeing if ayone had anything to say about this.

 

yeah, you will need to recalibrate it.

Bryan

 

how do i go about doing this? The place I talked to (same place I got to install my wheels) said that they don't know of anyone around my area that can recalibrate the speedo. I also believe that these guys would know b/c they do work on high end luxury cars and are good at it too (didn't find a scratch on my Z2's, and those are some hard wheels to put a tire on)

 

The difference is 25.2 inches vs 25.7. About %2, this would not require a change to the speedo normally, unless of course you really wanted to.

 

I don't think anyone has ever determined where the speed is read from, have we?

I went from 17s all around to 18s in front and 19s in rear, then threw in a 3.76 LSD. Try to get your brain around that one for a while.

https://www.clublexus.com/forums/sho...ht=do+the+math

I never could tell a large variance in speedo readings.

I don't think it's worth investigating. If you're really bent on it, try posting a question in the Maintenance Forum where one of the Lexus Techs may be able to help out, or you could always call your local dealer.