I have put on 20" American Racing wheels with Goodyear Eagle GT2 tires and I need to know how to calibrate my speedometer. Thinking everything is computerized now I called Ford to see if they can do it and they said that they can't. I tried the local speedo/tach shop and they said they can do it in June maybe, at a cost of $500. Seems steep to me. Any ideas out there?

Thanks.....

 

I went with the exact same set-up as far as wheels and tires myself. My Ford dealer is also at a loss on how to properly calibrate the speedo. They told me that all they could do is to follow my pickup with a stock one to see how far it was off. I called a local speedo calibration place here in Houston, and they claim that they can do it, but it will take some re-wiring. No price yet, but I will report back if I decide to have it done.

In the meantime, I'm taking to my local Kwik Kar lube and have them put it on the Dyno that they use for inspection and see exactly how far off it is. I may just live with it.

 

I had a mustang that came into the dealer the other week. Someone had put lower gears in the rear. There was a device installed called speedcalc that was attached to the Output Shaft Speed Sensor and to power and ground. Very simple installation. We ordered another one for the parts managers son's car but havent installed it yet. I opened it up and there are dip switches inside that I think you change to correct speedo reading. I'm pretty sure the phone number is 1-800-mustang. It cost the dealer about $120.00 but dont know if it included shipping. I got the new one layin on my bench at work. I will check the instructions and phone number today and make sure they are correct. They also have a web site that I will get the name of, and post later from work if I can remember.

 

Hey, I just found this web site which will do the tire size calculation difference for you. It's located at:

http://www.1010tires.com/tiresizecalculator.asp

I put in my old stock wheel/tire size and my new ones and I found out that I have a circumference difference of about 6" and a speedometer difference of 6 mph @ 60 mph. Doesn't seem like much really but it gave me a warning that anything over 3% (I have a 6% difference) could cause braking problems.

late.....

 

I just use the speed feature on my GPS. Stock tires I was 1-2 mph under, new tires 3-4 mph over. Gotta love the extra warranty. haha