265/75/16 tire switch

[Bear8664]

Hi I have 245s on factory alluminum wheels now and would like to switch over to 265/75/16E.I asked the dealer about this and was told that I would loose power and the transmision shift points would be diferent and the spedometer would be off. I know other people have done this to there rigs need help any advise would be appriciated.
Dan

[Chris N5CWM]

What brand tires do you currently have? Are they Firestone Steeltex R4S? According to the Firestone product info (http://productcat.bridgestonetire.com/exports/pp_13047.pdf) the 245s are turning 683 RPM versus 265s at 657. That is only a 2-3 MPH difference. Shouldn't be enough to cause problems. Your speedo will indicate 2-3 MPH slower. In the pre-computer days a different speedo gear would fix that. Now with the computer age, you'd think that recalibrating the speedo would be a snap. Seems as if a few dealerships are giving customers a hard time when it comes to chaning tire sizes.
I was at a local dealer looking at a demo 2500HD Sivlverado, and overheard two employees (service manager and salesman) talking about a customers' truck outside which had quite large tires on it.
I heard them say the warranty was void because of the tire size change! :confused:

[Modified]

Larger tires won't Void your warranty, they just may not work on it till you bring it back with factory size wheels and tires..
See TSB Info :

Info Inspection - of Tire and Wheel Size Prior to Diagnosis for Transmission Shifts, Poor Performance, Speedometer, Cruise Control Concerns #01-03-10-010B - (10/14/2002)
Inspection of Tire and Wheel Size Prior to Diagnosis of Transmission Shifts, Poor Performance, Speedometer, Cruise Control Concerns

2001-2003 Chevrolet Silverado Pickup Models
2001-2003 GMC Sierra Pickup Models
with Duramax

[TH]

FYI...new trucks are showing up in dealership lots with 265 tires as stock. I've seen them myself...

As well, these size of tires appear in the programmable computer for your truck when it comes to adjusting the ABS system.

Check it out...

[TH]

Sorry...should have added that I purchased 255/85R15 tires (slightly taller than 285s but only have way between 245 and 265s in width...

I went to the dealership and they recalibrated the ABS for the 265 tire as it was the largest diameter tire that they could find in the database for my truck.

I have a 2004 2500HD.

[64postcarnut]

What am I missing here? :confused:

Stock tire size is LT 245/75R16.I(or Bear8646) want to change to LT 265/75R16.The "rollout" of these tires should be identical.The only difference being the width.

How does that screw up the computer?

[Professor]

carnut

The 265s are an inch taller. About 27 revolutions per mile less than the stock 245s.

Professor

[64postcarnut]

Thanks, I subsequently discovered my error this morning ,but didn't have time to delete.

[310-MAN]

Bear....I went to the larger size tires on my 2001 (265/75R/16) If you want to see what the truck rides/performs like, "E" mail me. John jgr3418598@aol.com

[Runaway]

Hmmmm, that means if 265's are running apprx 4% slower than 245's. On my truck where the speedo is off 2 mph (per GPS) ie: to run 60 mph I have to post 62 on my speedo. Theoretically I could go to 265's and not have to change any settings in the trucks computer. Could have a better truck profile and an accurate speedo...maybe

;)