Page 1 of 1
How to Change tire size to fix speedo
Posted: Mon Apr 21, 2008 10:51 am
by betz
On my 2005 astro, is it possible to change the tire size in the computer so that the speedo isn't so far off?
Re: How to Change tire size to fix speedo
Posted: Mon Apr 21, 2008 12:52 pm
by Rebel
Re: How to Change tire size to fix speedo
Posted: Mon Apr 21, 2008 12:55 pm
by betz
I was under the impression that this was a setting that could be changed in the van's computer. I brought it to my shop today, but they have a new snap on scan tool that they don't know how to use yet. Thought that maybe someone else would know what to do.
Re: How to Change tire size to fix speedo
Posted: Tue Apr 22, 2008 4:48 am
by peter
The solution to your problem is as simple as purchasing a Hypertech Power Programmer. Buy one for your truck and you'll be able to compensate for tires/gearing etc. As well, you can select different performance levels thru the same programmer. Real simple and a fun tool for the backyard mechanic!
Re: How to Change tire size to fix speedo
Posted: Tue Apr 22, 2008 7:03 am
by betz
Peter, do you have one of those? If so, what is the exact model so that I can be sure it will work?
Re: How to Change tire size to fix speedo
Posted: Tue Apr 22, 2008 7:08 am
by Rebel
I was under the impression that this was a setting that could be changed in the van's computer.
Surprised Peter didn't inform you that I'd be last to know anything about the computer in our vehicles.
Re: How to Change tire size to fix speedo
Posted: Sat May 03, 2008 4:09 pm
by phr1$k37
betz wrote:Peter, do you have one of those? If so, what is the exact model so that I can be sure it will work?
I have the JetChips Super Programmer to change shift points, tire size and fuel rating (which is now back to low octane lol). I really did not see any performance except at WOT and even then it was super great. But the tranny stuff - THAT worked and is worth it imo. As well I have the vette servo in 
Re: How to Change tire size to fix speedo
Posted: Sun May 04, 2008 8:51 pm
by betz
Just wanted to mention I got the hypertech energy max. This thing is great. I was able to adjust my tire size, so the speedo is pretty darn accurate now. I have also been having a fun time messing with my shift points and what not. It is also great to be able to read my own codes and clear them when needed...like when the gas cap doesn't seal properly!