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Getting "tuned"...

sciggs

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sciggs Enthusiast

sciggs

Posted
Posted

i've heard many people say on here that after you get a bigger set of tires you need to have your truck tuned. What exactly does this do and where can you get it done?

 

 

thanks :)

omegafiler Senior Enthusiast

omegafiler

Posted
Posted
i've heard many people say on here that after you get a bigger set of tires you need to have your truck tuned. What exactly does this do and where can you get it done?

 

 

thanks :)

 

You'll just need something that will update your PCM so that it knows you have larger diameter size tires. It'll mainly just fix your speedo.

 

Just about all hand held tuners will do this for you, as a bonus. Or, just swing by your dealer (or any shop with a tech2), and they can do it for ya as well.

j.roffel Senior Enthusiast

j.roffel

Posted
Posted

Beat me to it.

 

 

They are reffering to having the settings in the ecu, your trucks computer, changed to reflect your current tire size. This is done to correct the spedometer so that it will read the correct speed. If you google it you can find out just how much difference there is between your old tires and new, speedwise that is.

 

Hope this helps,

 

Jon

 

 

SS Crew Enthusiast

SS Crew

Posted
Posted

I changed my wheels and tires on my 07 2500HD from the stock 17's to 20's and my dealer wouldn't change anything that wasn't a stock item, but he did reprogram the tire air pressure sensors from 75 lbs. to 45 lbs.

 

Now if I could just convince the dealer to remove the torque control management.............

Kevin.Jefferis Enthusiast

Kevin.Jefferis

Posted
Posted
i've heard many people say on here that after you get a bigger set of tires you need to have your truck tuned. What exactly does this do and where can you get it done?

 

 

thanks :)

 

You'll just need something that will update your PCM so that it knows you have larger diameter size tires. It'll mainly just fix your speedo.

 

Just about all hand held tuners will do this for you, as a bonus. Or, just swing by your dealer (or any shop with a tech2), and they can do it for ya as well.

 

 

 

Do the handhelds have specific tire sizes to choose from or are the sizes manually entered?

Paul58 Enthusiast

Paul58

Posted
Posted
i've heard many people say on here that after you get a bigger set of tires you need to have your truck tuned. What exactly does this do and where can you get it done?

 

 

thanks :)

 

You'll just need something that will update your PCM so that it knows you have larger diameter size tires. It'll mainly just fix your speedo.

 

Just about all hand held tuners will do this for you, as a bonus. Or, just swing by your dealer (or any shop with a tech2), and they can do it for ya as well.

 

 

 

Do the handhelds have specific tire sizes to choose from or are the sizes manually entered?

 

 

It depends on the Tuner, I've seen some that use tire size, i.e. 285/70-17, and others that use the tire height, i.e. 32.5". I think the ones that use the actual tire height are more accurate because through my research, the same size tire can vary as much as 2" between different manufactures.

Paul58 Enthusiast

Paul58

Posted
Posted
so they won't do this at a dealership? I will need to buy my own tuner?

 

 

SuperChips just came out with a hand-held called the Tire Paq. It's about $225.00 and is supposed to adjust your speedometer and odometer for changes in tire sizes and also adjust transmission shift points as well. It doesn't have the capability of tuning the engine, but can be upgraded to a SuperChips Flash Paq with tuning capability later if needed.

Kevin.Jefferis Enthusiast

Kevin.Jefferis

Posted
Posted

My dealer tried but said he could not put my 295/75 r16 in, he said the largest he could go was 285. I thought he went ahead and put in the 285, but after testing my spedo. it is still off by the same amount. After reading on here, I'm going to order a tuner, but wanted to make sure it would have my current tire size.

Guest 007FL

Guest 007FL

Posted
Posted

In a truck, more important than the speedo is the fact that the computer also controls the transmission shift point. Correcting the tire size readjusts those as well. Very important if you are towing or hauling heavy loads.

 

In my '03 when I adjusted the tire size it threw a T/C light at me. It was an unknown problem with the Hypertech at the time. I could get close but not exact to my 20" tire. With the Hypertech I had to measure the rolling circumference (with chalk marks on the ground) and use that value. Not sure if they still do it that way or not.

omegafiler Senior Enthusiast

omegafiler

Posted
Posted

It's just a bit easier if the PCM already knows what size tire ya have so you don't need to mess with it on your tuner. I had actually taken my '00 Tahoe to the local dealer just for a PCM update (it had some nifty shift/perf/idle improvements), and they updated it for my 285 BFG's without even asking.

 

And this was a GMC/Pontiac dealer working with a moded truck well out of warranty. But they're a pretty cool dealer - never had any issues w/ 'em. Needless to say, they've always got my business.

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