Hi
First post I have a 2006 LT1 HHR. I want to go from a 25.3 inch
stock tire, to a new 26.1 inch tall tire. Can i get the computer
reprogrammed at a Chev dealer to recalibrate for the bigger tires?

Thanks

 

Welcome Lena, you should not notice a difference, but test fit one on the front to make sure they clear everything...

 

There will be a 2mph estimated difference between those two sizes. The dealer should be able to reprogram the computer or you can take your cluster apart and reposition the speedometer needle.

 

I'm pretty positive anything under 26.4 diameter will fit.

 

Dealer may not touch it because it will still be within the range limits..not really necessary anyways..

 

A while back I added 26.1" tall 225/50/17 tires, clearance to strut was only
.300"

Speed-O diff seems to be more accurate..

 

seems these cars are about 3 mph slow from the factory..I bumped GPS..speedo ..mile markers and roadside speed checkers..gps is right on..speedo is not. Maybe they knew we'd be playing with the tires..

 

There is a difference between the two factory wheel sizes anyway. The 17 in tires are .15 inches taller than the stock 16's....however your size diff is way more than that. Your increase is like going from a 55 series sidewall to a 60 series. That is over %3.2 larger.
You may have some other issues besides tire clearance. It will change your shift points if you have an auto tranny...plus your cruise control may not work as well. It might increase your hwy fuel economy, but decrease your city economy....
Lastly, the higher drive ratio will make your first gear clutch work harder.

 

My tires are .600" taller that oems' & actually seem to have Improved the shift points / etc.....

Cruise works fine, hi-way mpg is of course improved.. City is still excellent as well.. My taller tires are also 3 lbs lighter (each tire)..

Don't sweat the small stuff...

 

X 2 , many, many members have changed tire sizes, besides we can't leave things alone..