JohnDeere

Hello,
I'm new to this forum and also new to Chevy.... Just bought a 2009 Chevy 1500 Crewcab and I love it!!! I did however notice that the speedometer is off just a little. The truck has 20" tires and I think that is some of the problem. I took it out tonight with my GPS and at 60 mph on the speedometer the GPS shows 62 mph. At 70 mph on the speedometer the GPS shows 73, and at 80 mph on the speedometer the GPS shows 84 mph. I was just wondering if there is a fix for this. Is this something the dealer can do? Is there some aftermarket device that will fix this? Thanks in advance for any and all input and help!!!

basilkies

The dealer can fix it or any person or mechanic that has just handheld computer equipment that plugs into your truck. Its a simple little reprogram on the tire size. The dealer is of course the most expensive. It always surprises me that tire shops don't do this since a 200 dollar device can do it.

MDTAHOE

There is no $200.00 device that any shop can use. The $200 device is a hand held programmer like a hypertech. They are 1 vehicle use once you use it on 1 you can not use it on another unless you remove the program from the first one. Also it is not 1 programmer fits all. It may fit several year/model trucks but it will not work on other makes. The dealer could do it however may not want to due to liability. That little bit off does not seem like enough to worry about.If it has the correct 20" tire the overall assembly will be exactly the same as the original size as I have done with my truck.

slw210

Why would you have a 20" tire on Full Size Pickup Truck?

I am guessing you mean wheels are 20", which means absolutly nothing to the speedometer.

What is the diameter of the tire? What tire size came stock on the vehicle? What is the tire air pressure?

More important, what is the rolling diameter of the tire?

Remember, stated tire sizes are NOT the ACTUAL diameter and are not the rolling diameter. It can vary from tire brand to tire brand, most will have the ACTUAL diameters on their websites.

If under warranty dealer should adjust it for you, if not use the GPS or buy the programmer.

basilkies

This device looks like it programs speedometers ; Tacho Pro 2008 Plus Unlock Jan Version Universal Dash Programmer

Like most stuff on the internet it's hard to figure out exactly what all it does, but it claims to fix speedometers and read repair codes. It also works on a lot of models and costs 239 dollars.

JohnDeere

Thanks for all the help!!! I think I found out why the speedometer is off... I got the build codes and they say it was built with 17" wheels. Well it now has 20" wheels so I think I will take it back to the dealer and see how much they would charge to fix it... Thanks again for the help!!! This is an AWESOME forum!!!