FWD - One rear tire with mismatched tread

I recently discovered a nail in one of my tires, too close to the sidewall to repair. The remaining three tires are wearing evenly with 5/32 of tread remaining*. I found a used tire of the exact same brand, model, size and speed rating with 8-9/32 of tread. Can I safely put such a tire on the rear of a front wheel drive vehicle and leave it there until the remaining three tires need to be replaced (at which time I would replace all four tires at once) or would that be inviting mechanical or handling issues?

*On a side note: does anyone find that much tread wear excessive after 20,000 miles on tires with a 45,000 mile warranty?

No problem IMO. Tread wear seems OK too.

Depending on the road surfaces in your area and your driving style you may never come close to the mileage rating of your tires. I never do. If your tires are wearing evenly, that is about the best you can do.

Dont worry about it,these other are going away soon.

The rear tire you want to put on will be fine. It will take a lot more difference in size before you’ll ever be able to notice it.

Thanks, that’s a relief! I’d rather replace all four tires at once instead of just two at a time – just not right now. I had searched for a long time online and found lots of conflicting information regarding the use of one or two mismatched tires, but all of it based on different scenarios. The consensus seemed to be that the discrepancy would be bad for the differential and that’s understandable, but I couldn’t find any information regarding use on the non-drive wheels on a FWD vehicle.

In my younger (poorer) years working pumping gas, the tires I used on my cars were the scrap ones we took off customers’ cars when they bought new tires. If any of them still had 5K miles left on them and the rim size was the same, I threw them on my car. My labor was free. I never had a problem.

Reflecting on that today, I would not do the above on an AWD vehicle, or if the vehicle was still under warranty. If it was 2WD on the same axle, I’d make sure the tires were at least the same size or were close in circumference.

It won’t be a problem, as long as that used tire is in fairly good shape

The tire wear you’re referencing is quite normal for 45000 mile tires

One more thing . . .

Are all of your rims the same, at least?

Meaning, are they all the same width and offset?

Yes, all my rims have the same dimensions and are still original.

The two rear tires are just along for the ride. They hold up the back, but all the drive is done by the front and the differential is in the front, too. That used rear tire will be fine as long as it’s in reasonable shape now.

The rear tires are important for tracking and Going straight while braking and taking corners under control and are what the rears are all about. The more weight you put in back, the bigger this factor becomes. As long as people drive on dry pavement it should not be a problem with mismatched treads. But, if a rear tire has significantly different traction on poor surfaces, you will quickly find they are not just along for the ride.

That’s all true, dag, but what the OP is proposing sounds safe to me. I’m unaware of any evidence that two of the same make & model tires with 4/32 to 5/32 difference in wear have differences in traction significant to be dangerous.

But I will suggest that 5/32 is getting “down there” in wear. An all season tire typically starts off with about 9/32+ of tread, and the minimum legal is 2/32. IMHO 3/32 to 4/32 lacks sufficient capabiity to disperse water in a downpour. The OP should think about getting three additional new tires in the not-too-distant future.

the same mountain bike said: " … I’m unaware of any evidence that two of the same make & model tires with 4/32 to 5/32 difference in wear have differences in traction significant to be dangerous… "

Unfortunately, the evidence you seek has never been published because of the legal issues involved. Suffice it to say that Michelin stated to the Rubber Manufacturers Association (RMA) that a difference of 1/32 of an inch difference was NOT significant, but 2/32nds or more WERE measurably different - and the RMA took that into account when they published their latest pamphlets.

I Think The Inherent Stability Of A Particular Vehicle Is A Factor. Some Vehicles Are More “Forgiving” Than Others (Same With Boats And Aircraft).

Wheel-base, center of gravity, suspension system, steering, etcetera must all be factors. My vehicles are very forgiving and don’t have any bad habits. I’ve driven cars before that seem inherently unstable and feel that when push comes to shove, they’d ground-loop. One was a Nissan NXsomething. I’m not sure if they were all like that or I drove a bad one.

Anyhow, I know my vehicles and wouldn’t hesitate to put on a tire that the OP is considering. On the other hand, a high center of gravity, short wheel-base, narrow track vehicle would cause me to reconsider.


but 2/32nds or more WERE measurably different

“Measurably different” depends on the smallest increment that the measuring device can detect. That does not mean that it is unsafe or even detectable by the driver.

It does mean that the absolute limit of control is affected by a measurable amount, but since few, if any of us would actually drive on a public road at the absolute limit of control, the measurable difference is not a safety factor.

Now if a significant difference would be a safety factor as that could put the absolute limit of control down into the normal limits of driving for most drivers.

The OP might spend a few bucks to get the newish tire shaved down as given the difference in circumference here, the bigger tire will throw off the alignment enough to cause a different wear pattern to emerge that will shorten the remaining life of the other tires.

If it were me, and I had lost a tire with the set at 5/32", I’d go ahead and replace all four. Life’s too short to worry about tires.

@"the same mountainbike"
I guess it kind of depends. I had no problems doing that and worse when I was driving Junkers and going to school. But I seldom remember driving these Riggs more then 50 miles away and leaving the road in the winter was just an adventure. But, when I was providing cars for the kids and my wife, i did and still do everything by the book. When my wife jumps in her car with four of her friends for a week end of “drinking wine” everyone knows her car is one of the best choice of the lot as far as maintenance is concerned. Without question, everything matched. So I am with @keith

Generally, I am not concerned with one to two 32 inch difference either. But four or five…yep. Snow tires with 5/32 inch differences are easily detectable in traction difference on slippery going…why wouldn’t all season tires too ?

You make a good point Dag.
Toward that end, I repeat my earlier recommendation: “The OP should think about getting three additional new tires in the not-too-distant future.” Perhaps I should have said “the very near future”.

So far so good. I haven’t been able to detect any difference in handling on wet or dry roads. If I notice any issues with traction/cornering/braking or the extra 1/4 inch or so of tire diameter impacting alignment, I’ll report it here. This tire is only intended to hold me over for a half year at most until the other three tires need replacing and four new tires fit better into my budget.

I’m late to the party but I blew a tire out 200 miles from home. I got to a tire shop just before closing and got a used tire put on to tide me over and get me home. No way it was the same brand or same tread depth-same size though. I had no problem with it and even went a couple months before putting new tires on driving every day.

As others have said, a lot will depend on the vehicle, driving styles/habits, and road/weather conditions. There is a possible difference in grip according to the article at the link below. Driving with extra care is probably the best idea.