Speedo Error caused by 22" wheels

[marlin1111]

All you guys with non standard wheels must have speedo error.

Here in Australia with speed cameras radar and anything else they can raise a buck, knowing your correct speed is important if you don't want to be a pedestrian!

I have 22 in with 245 35 22 on the car and my speedo is reading low.

At 100 kph (63 mph) on the speedo I am actually doing 107 kph & at 60 kph (35 mph) I am doing 64 kpm measured on a GPS.

So to the question, has anyone out there been able to fix the error caused by the over-sized wheels & tires, if so how. I have checked with my dealer & they cannot make the change to the ECU as the tire size is not on the list!!!

Marlin1111

[4u2nv]

Superchips Flashpaq. They have a tire size adjuster to fix your speedo.

[mavric01]

I have 22" wheels with 245/35/22 tires also, and my speedometer actually is pretty accurate. I've measured it with several other friends cars, and I'm only about 1 mph off at most from what their speedometers are saying. I've measured against 05 Vet, and 05 Mustang. I was told by Goodyear dealer that the computer would adjust itself to the correct speed automatically after a short period of time, and mine seems to have done just that.

Mav

[marlin1111]

Mav:

Not sure how the computer can reset the speedo, are sure he wasn't talking about the tires pressure sensors??

Dave

[tylerdeal]

well with my Pioneer AVIC N1 it comes with a thing called vehicle dynamics and it has a speedo on that, and my speedometer on my car is off about 2mph, it's a pretty sweet little program btw, tells you all kind of info.

[Flossin22s]

yeah mines 5 mph off, got a F-ing ticket one time cause of it

[RobAGD]

There are few things that MAY work with the dealer.

There are a selection of tires they can chose from, see if one is very close to your new wheel and tire diameter. If they dont have one ( they should have about 5 to chose from ) then you need to look into the flashpaq from Super Chips, but I am not sure they are good for cars out side the states. I would suggest emailing them and finding out the status on that.

From the factory my RT was off about 2-3 mph at 60 mph, with the Foose 20 and my 265 45 20 and 295 40 20's I am within .5 speedo to GPS using the SC to adjust.

-R

[300CN24S]

Yeah, mines off around 5 mph. A website you can go to and plug your stock tires in and then your aftermarket tires and it will tell you how much your speedo is off. I can't quite recall the site at the moment.

[Mr. iNCREDIBLE]

Originally Posted by marlin1111

Mav:

Not sure how the computer can reset the speedo, are sure he wasn't talking about the tires pressure sensors??

Dave

Superchips Flashpack has a tire adjustment in it to allow you to enter your tire size and it re-calibrates the Speedo to compensate for the new size, dealer can do the same thing with a DCX Starscan.

Keep in mind EVERYTHING on these cars is controlled by a computer via the CANBUS network and just about anything can be tweaked/adjusted within the computer to "fix", "update", or modify the vehicle.

and most cars since around 1991 have had electronic speedometers and vehicle speed sensors that can be adjusted via computer to compensate for tire size.

My 1993 Ford Probe
My 1996 Chevy Silverado
My 2000 Chevy Silverado Z71

All of these vehicles had aftermarket wheels in larger diameter than stock, and on all of them the dealer was able to "correct" the VSS (vehicle speed sensor) to accommodate my tire size..

[RobAGD]

Mr. I

Actually the dealer can only set to a range of preset tire sets, they cant actually "fix" most aftermarket tire sizes.

They could not let say correct my 29.4" setup nor could they correct my racing tires at 26.4"

But if you with in say 28.2 and 28.8 inches I think they have a few sets in those size ranges.

-R