So my 2004 Silverado had factory 235/75/16 originally and I replaced them with 2009 Tahoe wheels with 265/70/17. My GPS says I'm going 41-42mph while my speedometer says 40 mph. When I get to 70 mph, my GPS says 78-79 mph. I've always been told there is no such thing as a stupid question, but I got one for ya. If my speedo says one thing and the GPS another (faster), am I racking up more miles on the odometer or is it just the speedo that's off?
2010 Silverado ECSB LS 4x4. Only mods so far are a K&N drop in filter and a Rough Country 2" front level kit
The factory tires were 29.87" tall, your new tires are 31.6" tall. Did you retune the computer for the taller tires?
cjriojas:if you're weather man is a 5 gallon bucket, YOUUUUUUUUUUU might be a redneck
danger_ranger83: I see now why it cost so much to get a harness made... FML
2boostedSilverado: I like Casey's rear end, I want to chat with him about it
Yeah and after around 55 MPH is when you will see more of a difference. Lower speeds don't have as much of an affect.
2013 CC 5.3
81 C10 LS1 project
I haven't had it retuned. I guess thats something the dealer can charge me out the a$$ for. Maybe I'll call up there and see what they would charge.
you truck isnt tuned?
just get it tuned by a performance shop or a local "tuner" guy and they can adjust the speedo to the tire size you got.
2008 GMC Sierra
1998 GMC YUkon 4X4
2007 Kawasaki Vulcan 900 Custom
So I called the dealership and they want $98.00 to retune the computer. He also mentioned I might be able to disconnect the battery for a while and it might reset and learn the new size. Anyone heard of this? I would hate to buy a programmer just to retune the computer for this one thing. LOL, no it isn't tuned. I would like it to be, but I don't know what I would like done.
Last edited by medic2967; 08-30-2010 at 02:03 PM.
havent heard of disconnecting the battery and the comp learning the new tire size... i doubt it.
just get it tuned by a performance shop. just depends what you want your truck to do? speed, towing, MPG ... they can tune your truck for whatever you want, and you might as well have them fix the speedo to the new tire size.
2008 GMC Sierra
1998 GMC YUkon 4X4
2007 Kawasaki Vulcan 900 Custom
I called a somewhat local tune shop that specializes in LS based engines. They gave me a price of $350.00 with a Dyno run before and after. I could probably just do a Nelson tune for that.
Live tune is better than a mail order. Plus you get some time on the dyno.
cjriojas:if you're weather man is a 5 gallon bucket, YOUUUUUUUUUUU might be a redneck
danger_ranger83: I see now why it cost so much to get a harness made... FML
2boostedSilverado: I like Casey's rear end, I want to chat with him about it
unless hes got a good amount of mods (ex. cam, SC) i dont see a run on the dyno for a tune necessary IMOOriginally Posted by Duct_tape123
2008 GMC Sierra
1998 GMC YUkon 4X4
2007 Kawasaki Vulcan 900 Custom
Posting Permissions
Reply With Quote