How did you recalibrate your speedometer after larger tires?

I am going to be upgrading to 285 Duratracs very soon and I was wondering if anyone had any info on the Hypertech Speedometer Calibrator tool. I know the speedo will be off a bit after the change in tire diameter. This calibrator tool seems very simple and easy to use as it just take apart the dash cluster and plug it in.

I have researched various threads, but I thought this could be a "mega-thread" of sorts.

If anyone has any info on the Hypertech Speedometer Calibrator or if there are any other tools people like to use, please post here.

 

I used a GPS to see how fast I was going at certain speeds. No I have reference points and can pretty much guesstimate where I'm at at any speed.

 

I installed the Hypertech speedometer calibrator. Works fine for me. 2011 "old style" speedo cluster. The first one they sent was no good and I had to have it replaced under warranty. However, I had to remove the instrument cluster - and plug it "in line" between the harness and the cluster. So the install is more involved than you suggest in your original post.

 

FIFY

Contacted AutoAnything and Hypertech and they both confirmed that the original person I spoke with at AutoAnything was wrong. I will have to take apart the gauge cluster and do it that way. Not sure why they won't make an ODBII port programmer

I think I might just bite the bullet and purchase it. Their deal is $25OFF 199.99 or more plus free shipping.

Any other suggestions?

 

I haven't really dug into it but I think the root cause is something like that Toyota encrypts all their ROMs to prevent hacking aftermarket chip programmer tools.

 

That really sucks

I went ahead and bought it anyways. Used a coupon code for AutoAnything and got $40 OFF with free shipping. Hope I made a good choice

 

Should have waited some people have found their speedos to be more accurate with the larger tires. Mine was only off by 3 mph after I went to 33's. No clue how it happened but it did.

 

But, officer!

 

First I figured out the weight difference and subtracted the surface area of the old tire from the SA of the new ones, then I didn't. I just guess.

 

Your speed will always be off by a % not a set number. If you are off by 3mph at 20 youll be off by a lot more at 70.


With 235s mine was off by about 10%, went with 31s and im off in the other direction about 5.

 

Mine was showing according to gps at 65 mph on the speedo my gps showed 67-68