Just stuck a pair of Kumho KU 15s on the fronts, all I could get at short notice, apparently they are a "street legal race tyre".

Fairly new tyre that. Treadwear is 220 so it should last reasonably well. Don't really know a lot about them.

Unfortunately the treadwear number can't be taken as true metric ~ as I understand it each manufacturer selling to the US is required to rate each tyre against a proposed baseline. The manufacturer is free to choose whatever tyre they like as a baseline, and that is subjected to various tests and given a nominal score of 100 for wear.

All other tyres must be marked against this benchmark ~ a "treadwear 220" Goodyear therefore wears 2.2x better than the Goodyear benchmark tyre, but you have no idea how it compares to a "Treadwear 220" tyre from Pirelli for example.

It's in the interest of every manufacturer to set a quick wearing tyre as their baseline, so that the others in their range perform well against it. This is why you don't often see "Treadwear 50" on tyres

My Kumho 712's (in w-rating) are TW280, but have excellent wear characteristics.

Toyo Proxes T1-S is also 280, but apparently wear pretty quickly (not run any T1-S's though).

So mik's summary of the Treadwear Nunmer....... one nanomicron above useless :thumbdwn:

Now I'd disagree.

I've found with the ones that I've tried that I can roughly multiply it by 10 and that is roughly what I get if I rotate them part way through their lives. Gues it's just the ones I've used.

Oh and Pirelli P Zero Corsa, TWI is 40; P Zero C is TWI 60 IIRC, Kumho Ecsta V700 is 70, Dunlop Supersport is 70, Pilot Cups are 50 IIRC

Well now you've got me hunting for info on a friday night. Wife is out & have just got the kids down.....I should be searching for Pron

Anyway - there appears to be some conflicting info and I couldn't find a definitive answer from an official looking source....

It's most defo US driven. I found a number of webbies that stated the Treadware rating is against a "govt std tyre" which is assigned 100.

Other places like THIS SITE describe it as I believed it to be:

" Each manufacturer rates their tire in comparison to their own base rated tire and establishes their individual rating guide. "

BUT

I then found an excerpt from the CFA (Code Of Federal Regulations) Over Here which I don't expect you to read - 'tis the usual US regulatory legalspeak nightmare......and it does indeed talk about comparison with "Course Monitoring Tyres".... so it looks like you are correct sir.

So....... now you have to explain why everyone moans that T1-S's wear out quickly when they are rated 280 for treadwear. :confused:

30-15 ....

I'll have a go Mik, although I'm probably wrong.

The clue is on page 946 of the document you linked to

(v) Subject candidate and course monitoring tires to ``break-in'' by

running the tires in the convoy for two circuits of the test roadway

(800 miles). At the end of the first circuit, rotate each vehicle's

tires by moving each front tire to the same side of the rear axle and

each rear tire to the opposite side of the front axle.

followed closely by:

(viii) Drive the convoy on the test roadway for 6,400 miles.

(A) After each 400 miles, rotate each vehicle's tires by moving each

front tire to the same side of the rear axle and each rear tire to the

opposite side of the front axle. Visually inspect each tire for

treadwear anomalies.

I'll leave out the maths of how it is calculated as that really is too much for a Saturday morning. Suffice to say that their method of testing involves a route of 6400 miles and the tyres are rotated every 400 miles. Surely no one would be so unscrupulous as to have dual compound tyres

I can't believe that any manufacturer could pockle the test Jon...... that would be immoral.

I'd love to see the Validation Studies for this test method too..... although (for any US lawyers watching) I'm personally certain that they are scrupulously clean & free from fudge. :P

PS ~ I did actually read most of that CFR document last night, and I consider you a fartnocker for making me do it....... :thumbdwn:

HTH

The tyres are great by the way ! I've never before noticed such a dramatic improvement in handling just from fitting new front tyres. The steering seems more precise and more responsive. Done 700 miles since I put them on and delighted with them - not tried them in the wet yet though, and don't know how long they'll last (I got 10k miles out of my front Toyos)

Having seen a pic of the tyres, my first thoughts are they don't look like they'll be too hot in the wet...

...so, it will be interesting to hear your opinions, especially compared to the Toyo Proxes T1S, which when I ran them on a previous car, seemed to grip better in the wet than the dry they were that good!!

On another note, any-one tried the Kumho 712's??

EDIT: Just done a search & found the previous discussions