Will 34” tires create drivetrain issues?

Dudeguyman · Aug 17, 2023

Hey, guys. Anyone with bigger than stock tires ever run into any issues with transmission and/or differential problems? Reading into bigger tires and these are issues that get overlooked apparently but curious if anyone has ever had problems. Also would relearning TCM be hoo of me? Looking to go no bigger than 34”. FYI, I don’t plan on towing much of anything, maybe 3K LBS at most once a year if that. Can’t find anything on this subject with the known problematic transmission already.

Literally just replaced whole transmission (under warranty) so I’m nervous to do anything that may jack this thing up again. Dealership found large shavings inside transmission that created transmission knocking from the auto-stop feature - turned it off as I was stopping and thought I got rear ended…BAM…see ya transmission but no lose of power just knocking directly correlated with the RPM’s. Owned my 2020 duramax AT4 (bought used) for literally a week and took a month to get back to me, all good for now though.

kobra357 · Aug 17, 2023

I think if you get your speedometer calibrated you should be fine.
If you lift it then that’s another story.

yousefabdallah59 · Aug 17, 2023

Dudeguyman said:
Hey, guys. Anyone with bigger than stock tires ever run into any issues with transmission and/or differential problems? Reading into bigger tires and these are issues that get overlooked apparently but curious if anyone has ever had problems. Also would relearning TCM be hoo of me? Looking to go no bigger than 34”. FYI, I don’t plan on towing much of anything, maybe 3K LBS at most once a year if that. Can’t find anything on this subject with the known problematic transmission already.

Literally just replaced whole transmission (under warranty) so I’m nervous to do anything that may jack this thing up again. Dealership found large shavings inside transmission that created transmission knocking from the auto-stop feature - turned it off as I was stopping and thought I got rear ended…BAM…see ya transmission but no lose of power just knocking directly correlated with the RPM’s. Owned my 2020 duramax AT4 (bought used) for literally a week and took a month to get back to me, all good for now though.

I just bought a 2023 AT4X with 275/65/18 and I’m thinking 295/70/18 should fit for sure but I’m a bit worried on buying 34x12.50R18s and it rubs! If anyone has tried please let me know! I want to put 34x12.50s

Teegunn · Aug 17, 2023

34" tires will likely rub, especially if no front level. A lot of it will depend on the offset of your wheels. I have -19 offset 20x10 Fuel wheels with 34" Nitto RG tires on my 23 AT4X. Have a 1.5" RC front level, and even with a lot of trimming still have a slight bit of rubbing at full lock. Really wish the 2" level had been available for the AT4X when I had the front leveled, but the 2" front level kit was not available in January when I got my truck.

As far as drivetrain issues, there certainly is more stress/torque applied to the transmission, suspension and drivetrain. Obviously it is changing the gearing by 3 or 4%, and then the tires will be heavier than the 32" stock tires. I tow a lot as a contractor, and have had no issues and have not noticed anything negative with towing or driving from the larger tires and wheels. I have always put larger tires and wheels on my trucks - usually 33 or 34" tires (one time I went with 35" tires) - and have never had an issue. All of my trucks have been half tons and all have been used extensively towing heavier trailers. Knock on wood, but I have never had an issue.

I usually trade my trucks off after 3 to 4 years though, as that seems to be the sweet spot for wear and tear starting to pile up, but the trucks usually still have good trade value at about 70 to 80 K miles, so that is when I usually trade. So I have not had any of them longer-term to find out if the extra wear and tear from larger tires does a number on the drivetrain sooner than normal.

adeerchaser · Aug 17, 2023

I have a 2022 AT4x, have done zero lift to front end. I am running Toyo 285/70/18 MT’s (stock wheels), no rub, no cutting, no issues, mud flaps in place. Toyo site says they are 34.1 tall. Have done what I call mild off-roading, that is go where I want hunting, no rub yet. No driveline problems

Cocoabean · Aug 18, 2023

I have been running a 2" leveling kit with 35x12.5x17's for the last year with about 12k miles on the set up and have had no drivetrain issues.

Spowers723 · Aug 20, 2023

Cocoabean said:
I have been running a 2" leveling kit with 35x12.5x17's for the last year with about 12k miles on the set up and have had no drivetrain issues.

What leveling kit are you running? Is that 2” level kit in addition to 2” lift from factory?

Cocoabean · Aug 20, 2023

Spowers723 said:
What leveling kit are you running? Is that 2” level kit in addition to 2” lift from factory?

Ready Lift 2” leveling kit. Yes, this is on top of the AT4 2” stock lift.

phobby · Aug 21, 2023

A few things for you to compare;
1. Check each manufacturers specs on tire size. Bfg, Nitto, Toyo, etc- all state a “size” but their tire specs tell you actual size.
Ex-
nitto 35x12.5/18= 34.76” X 12.55
Toyo 35x12.5/18=34.5” X 12.5
Same goes for std sizing -285/70 etc

2. Check tire weight on their specs also. Weight per tire can vary also for the same size per mfr. Up to almost 10lbs per tire. I think tread depth, composition, and sidewall designs add some of this weight.

3. E and F rated tires will be heavier but D rated is all you need on a 1500.
-Less weight per tire- better on fuel and transmission.

When looking at tire specs go to the Manufacturer website, it’s not always correct on third party sites. Also it’s usually a lot easier on a computer browser than using their mobile page to see tire specifications. Ex- Toyo doesn’t label each tire spec and what it is on mobile browser.

note- your main issue with clearance is tire width turning. A 34 or 35 will clear on many gm trucks without leveling in a 11-11.5 where a 12.5” rubs. But look the exact same from the side of the truck.
-wheel offset will also cause clearance issues if you change wheels. idk why people take off $500-$800 per factory wheel on upper trim levels for $300-$400 aftermarket wheels that are heavier, other than they look “cool”.

Spowers723 · Aug 21, 2023

Cocoabean said:
I have been running a 2" leveling kit with 35x12.5x17's for the last year with about 12k miles on the set up and have had no drivetrain issues.

What tire and wheel setup do you have ? Offset and back spacing?

kobra357 · Aug 21, 2023

Im running Ready lift level with 0 offsett Fuel wheels 275/60/20 If I hit a bump while turning they rub Michelin LTX MS

Cocoabean · Aug 22, 2023

Spowers723 said:
What tire and wheel setup do you have ? Offset and back spacing?

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