KenC or any other tire expert: question about treadwear rating>>

[Pascalz28]

Tirerack claims that the treadwear rating is proportional
too the tires lifespan but others claim that a tire
rated for 140 will only last a "season of autocrossing".
But when you do the math it doesn't add up.

my tire treadwear is 300 and they're supposed to
last about 30-40,000 miles

so a 140 tire should last about 15-20,000 miles but
a "season of autocrossing" would be approximatly
equivalent to (20*4 = 80 miles)(rounding up)

so how long should the 140 treadwear tire last?

thanks,
P

[wolfdogs]

wanna know the truth about Uniform Tire Quality Grading????? (UTQG)


It's nothing but a joke. Yup.....a d@mn joke. It was developed by Dr. Cesal Brenner back in the late 60's due to an act of Congress which was passed in order to give tire consumers a better "idea" on making a "wise choice in tire purchase".

The test is a joke. the tires only run at 85% of thier max load...and only 6800 miles, 800 of which is a "break-in" course....

the tire manuf. gets a contract with one of the local testers in the San Angelo area when he needs some "numbers" . NHTSA does not even get involved at this stage... then the tester runs the test and turnes over the data to the tire manuf. the Tire manuf. can assign any number he wants to on the tire...... if the number is too high, the only way to find that out is for nhtsa to run thier own test under the exact same conditions of weather and all vararbles.... and thats pretty hard to do.....but i "can" be done.. but guess what.........its not done....and the tire manuf. know nhtsa does not have the necessary funds to "spot check" thier numbers..... if they get caught with too high of a treadwear grading number... they get fined. not too bad of a fine considering the tire industry is a billions of dollars industry. so.........what you get is tire companies assigning tires that show higher numbers ...lower numbers if that particular brand designation cost less than one of thier other tires that got a number lower... after all....if you went in a tire store and saw a "wolfmanTreadKing" tire by manuf. X that had a utqg rating of 400......and cost 88.88.........and another tire by mauf. x, the PascalRubberMongral that had a utqg rating of 330 and cost 99.99........yet both were rated the same in all other categories, which would you buy???????.. so...what manuf. x does..is asign the wolfmanTreadKing a 280 utqg rating......to insure more and proper sales of his PascalRubberMongral...

confused yet?

now... those "numbers" come from this: the nhtsa has whats called a "course monitoring" tire that is built and meets a specification for utqg testing. this tire is run right along side of the test candidates and treated like a test tire during each and every test. this tire represents the "baseline" for the numbers. this tire is considered a "100" utqg rated tire. so...at the end of 6800 miles... if the course monitoring tire had 1/4 of its tread left....and a test candidate had 1/2 of its tread left......the test tire coud be assigned................200.

here's more of the joke........ tread wear is linear... a tire wears faster after reaching a given tread depth depending on compounding procedures, cure, and casing construction... and to make things even more commical (ill deny i said this if questioned)...the tire manuf. do whats known as a "post cure" on the test tires for utqg..... not all of em..but some of them do. that makes the first few 1/1000th's of the tread extremely hard......which..wallllllllla........makes the number higher... then...because that hard rubber wears off in the tread wear test (which is done first under utqg)...it then goes to the traction test......and guess what..........its got soft rubber under that hard rubber..........waaaaaaaaalllla..... high traction letter......... LOL!!!

When i managed the Govt's Qualified Products List Testing program from 1983-1995.......my test was a 20,000 mile 100% of the max load casing durability/treadwear test. many times...i would take the treadwear number i got (we extrapolated the mileage to wearout) and compared them to the utqg testing data on that same tire.......guess what? the numbers were all over the board.......on the high side mostly........LOL

so.........heres the answer to your question.......

1. when they rate a tire 140.......its usually cause they know that tire will be used to "play with".......and its gonna wear out quick.... if you take a tire thats rated 300 and play with it........its gonna wear out like a 180.........

2. and if its autocross....the crown edge may wear out way before the tread...... if it does.....its because its a good tire.... .........why? beacuse the casing construction was "doing its job"........it was not letting the tire "slip" sideways.....or buckle...it was holding. if the crown edge did not wear out first...then you are slipping..and having to slow down........

more than you wanted to know? sorry.........

best way to buy tires for street, drag racing, auto cross, and whatever is to talk to tons of folks that have been doing it.......and find out what works and what doesnt.......

ride on broh.....

i will add..... the "heat" index number is pretty acurrate....

[Bond Hawk]

Autocrossing is much harder on tires compared to regular driving. You are constantly on the bleeding edge of losing traction when you autocross, so it wears the tires out much faster.

[wolfdogs]

Originally posted by Bond Hawk
Autocrossing is much harder on tires compared to regular driving. You are constantly on the bleeding edge of losing traction when you autocross, so it wears the tires out much faster.

it "feathers" the tread surface...due to side slipping of the treat blocks and traction grooves...... it also generates tremendous heat due to the constant hard flexing of the belt package, wedge supports, and cord body, which accelerates tread wear........

[fastTa]

Originally posted by wolfman
it "feathers" the tread surface...due to side slipping of the treat blocks and traction grooves...... it also generates tremendous heat due to the constant hard flexing of the belt package, wedge supports, and cord body, which accelerates tread wear........

Geesh

You don't know much about tires do you?

[Jeff_in_Atl]

Very good Wolffie. That took some time.

Interesting thing about the feathering, My 85 GT when it was stock feathered the tires really bad. When I converted it to the SVO suspension it completely stopped the feathering. The SVO's control arms were about an inch longer. The struts were also different and were kicked out at more of an angle. I guess it was enough to fix the geometry. McPherson struts suspension is still pretty lousy. When you turn the wheal, it casters the tire the wrong way really badly. I am so glad the 4th gens went back to upper-lower control arms. I can't believe Ford is still using McPherson struts. How old tech that is.

[Tundrahog]

My Kuhmo's are rated at 50......very sticky. I use them for autocross only.

[Injuneer]

Originally posted by Jeff 95 Z28
..... McPherson struts suspension is still pretty lousy. When you turn the wheal, it casters the tire the wrong way really badly. I am so glad the 4th gens went back to upper-lower control arms. I can't believe Ford is still using McPherson struts. How old tech that is.

Visual aids always help....

Mustang:



F-Body 4th Gen:

[Jeff_in_Atl]

Very good. Can you turn the wheel and watch the caster change? Did you do that in a FEM?

[wolfdogs]

Originally posted by Injuneer
Visual aids always help....

Mustang:



F-Body 4th Gen:

fred.....

u never cease to amaze me......

[crazilyconfused]

Wolfman.........I work for goodyear and suprizingly I understood every single thing you said. i can back that up. UTQG is nothing but horse crap. Each manufacturer is different. I think there was a post asking about this not too long ago. And the same thing was mentioned. They are performance tires, don't expect too much from them at all.

[wolfdogs]

Originally posted by crazilyconfused
Wolfman.........I work for goodyear and suprizingly I understood every single thing you said. i can back that up. UTQG is nothing but horse crap. Each manufacturer is different. I think there was a post asking about this not too long ago. And the same thing was mentioned. They are performance tires, don't expect too much from them at all.

i know quite a few of your Akron folks.....
small world.....

dont repeat what i said......hahahahahahahahaha

to Nhtsa anyway....

remember the aqua tread? look back in time at issues of Tire Business Magazine and find where it flunk our QPL test.... and yes...my name is there.... and yes.....Goodyear re-designed it...... cause it needed to be..... kudos.

[crazilyconfused]

sorry to jack this post but one more quick thing Wolfman. The new Assurance with TripleTred is 1000% better then the aquatred. Although I have yet to test the tire on ice traction.