Tire tread question (1 Viewer)

[Gohawks63]

Had a flat tire over the weekend and due to where the cut occurred, they couldn't patch it. The cut wasn't on the sidewall, but right on the edge of the treads (on the shoulder?). Instead of replacing the tire, I opted to put a plug in the damaged tire (it's holding air) and put the spare in service since it's full size, and use the damaged tire as a spare.

My question is what is the threshold on when you should replace all four tires due to tread variation?

The spare has never been used so it's basically new, and the other tires have 49K miles on them. A new tire has tread depth of 11/32. I just went in for an oil change and the tires were measured at 8/32, so there are 3/32 difference between the spare and the other three tires.

I spoke to the service department at my dealership and they told me that I shouldn't be concerned as the variation isn't that great.

Do any of you have any insight? I'd hate to have to buy four new tires since they all have quite a bit of life left, but I also don't want to damage the driveline.

Thoughts?

 

[NMuzj100]

If you're worried about the difference, a tire shop can shave the bigger tire down to match the others.

Matching Tires on four-wheel drive vehicles - From the Tire Rack

By two of three manufacturers recomendations listed in the article you are OK.

 

[Tinkerer]

I don't agree with the concerns voiced about the driveline:

The differentials are constantly "walking" as the vehicle veers from a perfect straight line. The Tire Rack article gives an example of 4 differential revs per mile for a given tire mismatch and says this could be a problem due to heat etc. But 4 revs per mile is only 1 rev per 15 seconds, at 60 mph - this will generate insignificant heat compared to the action occurring at the ring & pinion, at that speed.

Has anyone ever seen driveline problems confirmed to be caused by tire mismatch? The differentials are designed & built to be extremely rugged and tolerant of A-B speed mismatches, and manufacturers know that tires will not be perfectly matched on vehicles in service - heck, they become mismatched due to wear alone, because few owners rotate their tires per schedule anyway.

(Comment on differentials is not including design weaknesses, such as 2-pinion front diff in certain vehicles. Ahem. But even the 2-pinion front diff will not die young because of wear - it dies under extreme forces.)

But, I might be wrong. Anyone know of definitive test results? Notice that even the manufacturers recommendations vary widely, which says something.

(And keep in mind that some of the various mfg recommendations may be for vehicles with various viscous coupling and other type AWD, which may indeed generate excess heat and wear with mismatched tires. A gear-based center differential such as used by the 100 Series 4WD is completely different.)

Personally, the concern I have about tire mismatch is related to handling & braking, mainly. I want all 4 tires to be closely matched for that reason. How close? Virtually identical. Anything else has the potential for problems in extreme conditions, with potential increasing with increasing amount of tire mismatch.

The question is: How much tire mismatch can you personally tolerate, vs. how much money can you spend on keeping the tires matched?

I don't think there is much objective and definitive test data to reference here (notwithstanding biased opinion and conjecture such as the Tire Rack article).

 

[Travis351]

I had the same thing happen to me about 2 months ago, except it was a big screw in the sidewall and the tire could not be repaired. I put on the unused spare with my other 3 Michelin LTX/MS with 25,000 miles on them. I have not noticed any difference in handling or noises and it has been about 8000 miles. I bought the first one of my next set for the spare (BFG AT KO 285/75/16) and would be happy to sell the rest of my relatively new Michelin LTX/MS 275/70/16 to anyone who needs them. PM me if interested.

 

[Gohawks63]

I drove back about 180 miles straight and the truck felt fine, and I rarely take mine to extremes. So basically I'm hearing I should be fine.

 

[Jim_Chow]

I doubt you'll have any issues. I doubt all wheels are turning exactly at the same rate. Besides already mentioned factors like not driving in a straight line, roads are sloped for drainage, etc. Plus don't the '00+ 100-series have open diffs?