On a road trip, LR tire 265-70-16 got a big bubble. Pulled into Indy tire shop, the guy installed used 265-75-16. We drive another 200 miles, never noticing anything. No pull, no nothing. Look at new used tire the next morning, notice it’s a 75 instead of a 70. YES I know this is not optimal. Question is, it is a small difference not causing any apparent difference or problem, so can I continue? Is it negligible? Vehicle is 2004 Chevy Avalanche. 275K miles. Thanks for any advice.
70 vs 75 on rear
- Thread starter gfh77665
- Start date
Limited slip or open diff?
Not sure, it’s a base model. Stock.
Your RPO codes in the glovebox will tell you about the locking diff. G80 IIRC is one of the codes.
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GM RPO Codes - Axle Ratio and Differential Identification - West Coast Differentials
Use the GM RPO codes on the label in your glovebox or on drivers door to determine axle ratios and more. Decipher the factory codes and get the right parts!
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Even if it does have the G80, the rotational difference can't be enough to lock it or cause damage in my opinion. If it bothers you a lot. You could swap to the front OR add 5lbs to the 70 series tire opposite the 75 series.
i Personally wouldn’t want to keep it. Under harder acceleration and harder braking, it will pull. There will be additional wear to the diff, like you are in a mild turn 100% of the time. if it’s 4wd, I definitely would get rid of the 75.
It does not bother me at all. It’s fully unnoticeable after 200 miles. I was thinking the same, air up the 70 to the max and reduce the 75 by a few PSI for now. Since it’s an old truck and not a new car, I am thinking there is a bit more tolerance than most have.
Base 2 wd. Under heavy acceleration only the RR spins out.
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If it were mine I would replace it with the proper size when convenient. Its 3% difference which is a reasonable amount IMHO. Unless its something you drive 1000 miles a year.
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Open.
Why
To slightly alter their height. Not a fix but a slight change to get them closer.
So tell me how are you going to rotate those tires?
I am not. Even if I did though on the front there would be no gearing issues. Maybe a tiny pull if that. Thanks for your help.
Just following up, it appears that the height difference is about 3%, not ideal but not catastrophic. I have read some anecdotal postings about people discovering a tire one size off after 5000-10000 miles and nothing happened to their 2wd vehicle. Apparently there is tolerance built in, think a donut spare for short term use, for example. Also a brand new tire paired with a worn one, that’s a height difference too. No worse than driving a slight curve for extended intervals. I am not stressing, nor am I being cheap. I just don’t care to disrupt my vacation to deal with tires, and I like figuring things out, learning stuff.
Since it’s an open diff, it’s like you said, not ideal but not catastrophic. I wouldn’t drive it longer than necessary.
Update, I got home just fine. In 800 miles, the ole' Avalanche never seemed to notice there was any size disparity on the rear tires. I ordered a replacement tire of the correct size, and will drive it "as is" until it arrives in a few days. No stress, no concern, nothing exploded, all good!
Finally got around to installing the replacement tire. About 1500 miles and no issues with the 75. I'll keep it as a spare.
