CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Turn tires without moving VS tire wear

It seems a fairly accepted view that turning the front tires while stopped (or otherwise without forward or reverse motion) causes extra wear on tires.

This is NOT about how wear happens nor the possible consequences of the wear.

The question is whether tires with a lower UTQG rating wear slower, faster, or the same as tires with a higher UTQG rating.

Thoughts? Does the rating reflect “soft” vs “hard” tires and so one might wear more than the other when the steering wheel is turned without forward or reverse motion?

Yes, the UTQG rating are… lower number means the tire will not last as long as those with a higher number so it wears faster. Generally the tread will be softer and offer greater traction with a lower number than a higher one.

Track tires may have a 40 rating compared to 400 or 500 for other tires. The track tires stick to the track better than the 400 treadwear tires. The 40 treadwear tire will wear out very quickly by comparison to the 400 tires.

Seriously , just how often do you turn the wheels without vehicle movement ? Of course a softer tire will wear more by turning without movement . That will need to be done a lot to make any real difference in the life of the tire.

Disclaimer: I am not a rubber chemist. I’ve worked along side some very talented ones and have picked up a few things along the way.

First, the mechanism wearing away the tread when you turn the steering wheel while the vehicle is stationary is called abrasion. While abrasion plays a role in tire wear (and what the UTQG treadwear test measures), it isn’t the entire picture. Numerous studies have been done to try to accurately predict what the UTQG test results would be using lab abrasion tests, but none (so far) are accurate enough to be useful.

The reason these studies were done is that the UTQG treadwear test is expensive and takes some time to run, while a lab test is cheap and quick.

Second, the idea that “soft” tires are grippier is wrong in that there is a third possibility. There is a technology triangle involving treadwear, traction, and rolling resistance. Tires with good rolling resistance are also soft, but would not have good grip.

Mustangman mentioned tires with 40 UTQG treadwear rating. Unfortunately, tires with ratings that low are usually not even tested - values are just assigned to comply with the regulations. The regulations state that the ratings can not be OVERSTATED, but there is no penalty for understating them, so it is common for track tires to be assigned a low number knowing that no one will care if the number is accurate.

The problem with the UTOG testing is it’s done by each tire manufacturer, so there are variances from one manufacturer to the next. In general it’s a good starting point. I wouldn’t be concerned about a 400 UTOG rating to a 450 UTOG rating. But a 400 to 700…then I’d really take a look.

1 Like

Ah …. Mmmmmm …… not exactly.

The variability is inherent in the test. All the tests are conducted on the same public roads in Texas using a convoy of vehicles. While a tire manufacturer can use its own vehicles and drivers, it is more common for manufacturers to hire an independent lab who runs many tests at the same time, thereby reducing the cost.

The real problem is that the test is only 10,000 miles long and small differences in measurements result in fairly large differences in results. And that doesn’t take into account that weather is an uncontrolled variable. The manufacturer I worked for (and I assume all the others as well) have a lot of data where the same tire is run repeatedly over the course and the variability is obvious.

For example, each test is supposed to be run against the SRTT (Standard Reference Test Tire), a Uniroyal tire specially made by Michelin with certified materials and carefully followed in the manufacturing process and stored in a controlled environment until use. There is a lot of data on this tire over the UTQG course. Unfortunately the SRTT is an old size and only fits on certain cars, so it is permissible to use another tire as a reference - something more modern and more compatible with available vehicles (SUV’s for example.)

I’ve estimated that tires rated with 10% of each other are essentially the same. Outside that 10%, then those differences are likely real. One of the other problems is that pavement surfaces can drastically affect what a consumer experiences. for example, southern Florida uses “new” limestone and the sea shells can still be seen. Those sharp edges easily cut the rubber when the pavement is new, and it takes a while until the pavement wears off those edges.

Not to mention that most tire wear occurs in cornering, so driving in a straight line is almost free miles.

As a result, consumers can experience widely different wear rates on the same tire. My field testing has seen as little as 10K miles and at much as 100K miles from the same tire. Your mileage may vary!!

yes, and it seems you think that a “softer” tire will suffer more abrasion when turned without movement, or do you think it’s possible that it’s “softness” allow it to sort of stretch and release without as much abrasion?

I know some people who do it out of habit nearly every time they are maneuvering at low speeds in “tight” spots – that wear would be expected to add up, correct?

(and no, those people aren’t going to change their habit)

thanks for that
if there’s no correlation between UTQG numbers and abrasion suffered by turning without moving, then it would seem the numbers are relatively useless for cars with drivers who often (or frequently) turn tires without moving

You seemed to want to avoid that discussion… But yes, if there is more wear when turning sitting still, there will be more wear on a softer tire.

Yes, there is but it is not quantifiable. You can’t say if the OTQG number is double, the wear while turning will be half. Tires that wear faster in normal use will indeed wear faster if you turn the tires while sitting still. Although… the car’s suspension geometry likely has more affect but no one tests for this because it is an unimportant subject.

This seems analogous to wondering how high the ocean will rise if you pour either a cup of water or a gallon of water. I hope you won your bet.

No, no, no, no, no!

There IS correlation, it’s just not overwhelming.

But frankly, the idea of someone buying tires based on the UTQG treadwear rating because they turn the steering wheel while remaining stationary seems like a fixing the wrong problem. I would educate the driver to move the vehicle slowly while cranking on the wheel.

oh, ok (I must have missed it in your replies)

is the correlation that “softer” tires would suffer more abrasion? if so, is the difference very small even between “200” and “700” tires (for example)?

99.99% of tires aren’t suffering significant wear from turning while stopped, I’d bet…

??
I’ve NOT been trying to get exact quantified UTQG numbers in connection with this

the interest is in the concept – for example, if you say a 200 tire is “softer” and will suffer more abrasion than a 700 tire, is that based tests or experience or something else?

OTOH, if the correlation isn’t strong, maybe the difference in abrasion between 200 and 700 is very small

the people I know with that habit seem to think so too…

and then there are those (like me and others on this thread), who would prefer to have the vehicle moving when turning

Of course it’s better to have the car moving. But is it a problem worth worrying about? Not to me.

I’m certainly not worrying…

this came up in conversation over the weekend and it seemed a little interesting

[edit: some might say even thinking about “better” for a less than 0.01% effect is not worthwhile :wink: ]