reference for tires wearing faster when new?

[NissanMaxima]

Hi all:

It seems to me I have read some posts here where folks claim new tires wear faster when new and then the rate slows down and stabilizes. Does anyone have a reference for me that demonstrated this (at least for conditions they studied)? I just got some GoodYear WeatherReady all-weather tires for our Corolla. I have about 2k highway miles on them and using the depth rod on my digital caliper, (which I find is much more accurate than a standard mechanical tire tread depth gauge) they have started to wear at an average of 0.2/32" per thousand. Starting at 10/32" and at this rate, they will reach manufacturer warranty limit of 2/32" at 40 miles - long before the warranty of 60k miles. And, I should note we drive extremely conservatively and I routinely check tire pressure. If I project to 4/32" which I (and other respected organizations) believe is a much safer limit at which one should put on new tires, especially in snow and ice condition, that projects a lifetime of only 30k miles which, coincidentally, is about where I have found I needed to replace the first two sets of tires on this car. Perhaps some cars eat tires faster but I'll be monitoring the rate from time to time on this set as an interesting BITOG experiment.

The only reference I found was an interesting study done by this fellow, but it appears the slope of the initial wear rate is no different than during the life of the tire.
http://www.randomuseless.info/tires/tires.html

 

[ctechbob]

I would think some of it would depend on the amount of time the tire is in service along with the environment. If you put few miles on the car, it lives outside, and the climate is sunny and harsh, I would expect that over time as the rubber ages and hardens that wear would slow down. If you drive harder and use your tires up in a matter of a year or two I'd imagine the wear would be a lot more linear.

 

[Dave9]

I would wait and not jump to conclusions about the first %'s of tread. Even if the rest wears fairly linearly, the initial break-in will be the fastest wear rate. Additionally being an all season with a tread compound softness compromise, they should wear a bit faster in warmer months than colder.

Note in your tire warranty statement whether you might need proof of timely rotations.

Some cars definitely eat tires faster. For one, you have a *smallish* sized vehicle and there are larger diameter tires so all else equal, you'd expect a correlation between revolutions per mile and wear. If yours is a base model with skinnier tires, there's that too.

Frankly I never liked Goodyears for ice/snow/rain, they seem to get slippery after the first few years so at least for ice performance, I'd replace based on age rather than tread depth unless the tread is worn down past the siping.

 

[NissanMaxima]

Originally Posted by Dave9
I would wait and not jump to conclusions about the first %'s of tread. Even if the rest wears fairly linearly, the initial break-in will be the fastest wear rate. Additionally being an all season with a tread compound softness compromise, they should wear a bit faster in warmer months than colder.

Note in your tire warranty statement whether you might need proof of timely rotations.

Some cars definitely eat tires faster. For one, you have a *smallish* sized vehicle and there are larger diameter tires so all else equal, you'd expect a correlation between revolutions per mile and wear. If yours is a base model with skinnier tires, there's that too.

Frankly I never liked Goodyears for ice/snow/rain, they seem to get slippery after the first few years so at least for ice performance, I'd replace based on age rather than tread depth unless the tread is worn down past the siping.


Right! I'll have to post back at some point about future measurements. Regarding GoodYear, I really wanted the Michelin CrossClimate all-weather but it didn't come in my size. The GoodYear WeatherReady was almost rated as high on TireRack, Consumer Reports, etc. By the way, you mentioned all-season. Both of these tires are all-weather rather than all-season and are severe snow service rated although I fully know they are not on par with true snow tires.

 

[danez_yoda]

a lot depends on the tires design. i know michelin goes the extra mile with staggered sipping in their thread so they font have one ling sip for the full thread depth. it only goes half way them another set of sips (bubbles) emerge to serve the same function on the second half of tire wear. this is supposed to reduce "squirm" when deep sips are used.

I could totally see tire manufacturers using a softer outer compound for higher "initial quality" tire rack scores. then when the softer stuff wears down the longer wearing but less traction part kicks in and meets the warranty period claim. 100% speculation admitted.

depending on the weight of the vehicle it would also make since that the rubber compacts over repeated compression cycles during use. this would make the tread base harder than the outer part, harder rubber would wear longer and have less traction.


of course if the car loses alignment or air pressure during test period that could increase the wear rate is time goes on to counteract the hardening of the rubber.

it would be interesting to get a rubber hardness measurement of a new tire sliced into 1/16 thick slivers from top to bottom, then an old tire of the same make slice the last 1/16". and see if it is substantially harder. the tip of a balk point pen poking at the rubber would be a cross indication.

 

[CapriRacer]

A couple of thoughts:

1) Even though there is a published tread depth value for a new tire, that value isn't always accurate - sometimes it's even wrong.

When I was testing tires, I measured brand new tires and found that tires listed as - say- 10/32 new, ranged from 9.5 to 10.5. Further, the new depth wasn't the same across the face of the tread - and with no consistency. Some outside grooves were deeper, some were shallower, some the same.

While the new tread depth was generally fairly consistent around the circumference of the tire, as it wore, there was some variation around the circumference - to the point where I had to reject some tire's data if I was going to publish the data.

2) The wear curve is indeed a curve, however it is a slight curve.. It starts out wearing faster, then gradually the rate slows down.

This makes sense if you consider that the part of the tread that is being worn is at the end of a column - and the taller that column, the more movement takes place. That also means that the wear rate change is going to be dependent what changes as the tires wear.

Some tires have - more or less - vertical grooves, where others have tapered grooves. Some have "tie bars" - that is, in the groove there is a raised portion that stiffens the tread element thereby reducing the rate of wear. In other words, different tires will have different shaped curves.

The same applies to sipes. Some are full depth, some are quite shallow, and some are stepped.

3) For practical proposes, the wear curve is slight enough that using a straight line method is close enough - and it sure beats trying to figure out what the curve is and using that math to figure out a more accurate projected wearout mileage. I've tried and was unsuccessful because there was no consistency! Even on tires where I had a lot of data and had confidence I could characterize the wear curve fairly accurately, there was so much variability in the data, that it was clear that wheel position effects, and differences between vehicles (mostly how the vehicle was used) overwhelmed any attempt to get more sophisticated. I'm sure I could get this all sorted out, but I needed more data and needed to up my statistical expertise.

4) The biggest contributor to tire wear is how the vehicle is used - that is how much cornering vs straight ahead driving.

There was a test that simulated driving in the downtown area of a city. That test could wear tires out in as little as 5,000 miles, where other wear tests had wearout points in the 40K range - or more!

I used to test tires on courier fleets - delivering mail and packages on a set schedule, point to point. The routes that worked the downtown area wore tires much faster than the routes between cities (where even fast wearing tires could get 100K miles!)

5) Since most consumers drive in between the extremes, their mileage is ..... ah ….. Mmmmm …… in between. As a general rule, mileage guarantees are somewhat fanciful. Only the extreme drivers (like my courier drivers) could get those mileages.

That should have meant that there should have been lots of warranty claims, but that was not the case - because of all the restrictions listed. For example, there is a restriction against commercial usage of the vehicle - so couriers and taxi fleets aren't covered.

6) When it comes to warranty, there is a lot of variation as to how that warranty mileage is set. Some tire manufacturers are conservative and some are aggressive. So comparing warranty mileages is somewhat problematic.

7) The UTQG tread wear rating is probably the better gauge for comparing wear rates between makes and models.

The UTQG treadwear rating is based on a test performed in Texas over a prescribed course for about 10K miles. The rating is supposed to be a comparison to the SRTT (Standard Reference Test Tire), so in theory, you can compare not only between brand, but also between different models of tires.

Unfortunately, there is a lot of variability in the data, plus a tire manufacturer doesn't have to show what value they get - they just can't OVERSTATE the value. It is common for tire manufacturers to adjust 2nd and third line brands downwards to make the 1st line look better.

For this reason. I think that tires with UTQG rating within 10% of each other should be considered the same. Plus, many will find tires wear better than the UTQG rating comparisons indicate.

So I think when people report tire wear, you have to take it with a grain of salt. There is going to be a lot of variability in what people experience.

To the OP: To find that your newish tires are projecting to 40K is not a surprise. It's also not a surprise that it is well short of the warranty. That value will get larger over time, but it is unlikely to ever get to the warranty value. And without knowing the wear curve for that particular make and model, it is nearly impossible to get an accurate reading.

 

[novadude]

CapriRacer….great info! Thanks for taking the time to share all of that!

 

[GMFan]

I once tried to back into a calculation of wear-out point on some General tires I had on my car. My initial calculation after 20k or so miles was that I'd get 40k miles out of them and I was somewhat disappointed. However, they really started to slow down their rate of wear, and I ended up getting just over 70k miles on them, and they weren't even totally at the wear bars yet.

 

[jjjxlr8]

Don't forget weather! The weather makes a significant difference in tire wear rate. Tires wear more when there is more slippage.

 

[CapriRacer]

Originally Posted by jjjxlr8
Don't forget weather! The weather makes a significant difference in tire wear rate. Tires wear more when there is more slippage.


That seems to imply that when it rains, tires wear faster, and the opposite is true. The water acts as a lubricant and slows the wear rate considerably.

 

[supton]

Originally Posted by CapriRacer
Originally Posted by jjjxlr8
Don't forget weather! The weather makes a significant difference in tire wear rate. Tires wear more when there is more slippage.


That seems to imply that when it rains, tires wear faster, and the opposite is true. The water acts as a lubricant and slows the wear rate considerably.

That is interesting. Tires run cooler in the rain, no? Anyhow, I'm somewhat dubious how much "true" slippage is occurring in the rain, since that implies skidding or spinning. At least that is my first thought.

I'm contrasting this against dirt & gravel roads where I do believe tires are known to wear faster. I don't know if that is from slippage (tire spin) or friction with the road surface (as rubber hits an imperfect surface it's going to deform a bit around the rough edges). I wonder if water is the lubricant that reduces that friction of the tire deformation, and not true tire slip. [I probably have the tire terms wrong but I think I described what is in my head.]

 

[jjjxlr8]

I was thinking more about ambient temperature which affects compound abradability, stiffness, and the coefficient of friction.

Tire treadwear is extremely complicated and is affected by so many factors. But to the OPs question, the wear rate varies significantly when the tires are new for a variety of reasons. The wear rate starts much higher, then levels off.

 

[Ws6]

Originally Posted by NissanMaxima
Hi all:

It seems to me I have read some posts here where folks claim new tires wear faster when new and then the rate slows down and stabilizes. Does anyone have a reference for me that demonstrated this (at least for conditions they studied)? I just got some GoodYear WeatherReady all-weather tires for our Corolla. I have about 2k highway miles on them and using the depth rod on my digital caliper, (which I find is much more accurate than a standard mechanical tire tread depth gauge) they have started to wear at an average of 0.2/32" per thousand. Starting at 10/32" and at this rate, they will reach manufacturer warranty limit of 2/32" at 40 miles - long before the warranty of 60k miles. And, I should note we drive extremely conservatively and I routinely check tire pressure. If I project to 4/32" which I (and other respected organizations) believe is a much safer limit at which one should put on new tires, especially in snow and ice condition, that projects a lifetime of only 30k miles which, coincidentally, is about where I have found I needed to replace the first two sets of tires on this car. Perhaps some cars eat tires faster but I'll be monitoring the rate from time to time on this set as an interesting BITOG experiment.

The only reference I found was an interesting study done by this fellow, but it appears the slope of the initial wear rate is no different than during the life of the tire.
http://www.randomuseless.info/tires/tires.html


Sadly, I do not have data on that for you from a statistically sound source, but I can tell you my CrossContact LX25's lost 2/32 in the first 3K miles, and this last time they were rotated (total of 7K miles), they had lost no more tread, and are still holding at 8/32. My dealer actually legit measures this stuff. I've double-checked them and get the same numbers they do...

My WRG3's lost about 3-4/32 the first 5K miles, and 1-2/32 every 5K miles after that. I replaced them at about 19K miles.

My Toyo A36's followed a similar pattern.


Think about it...deeper tread=less tread stability=more movement/friction/non-optimal interface angle=more tread wear.