Tyre Laws
Author
Discussion

Bweemer

Original Poster:

25 posts

260 months

Wednesday 23rd June 2004
quotequote all
Could someone please clarify for me the laws on tyre tread. I run Michelin Pilot Sport Cups as std, which are road legal as they do have >1.6mm tread depth over 75% of the tread pattern. The tread pattern does not however extend over the whole contact surface of the tyre. What distinguishes this legally from a slick tyre where there is, of course, no tread pattern, so 75% of nothing is nothing - if you see what I mean. I appreciate I'm probably very mis-informed and very thick !

bsdnazz

762 posts

275 months

Wednesday 23rd June 2004
quotequote all
I thought the requirement was 1.6 mm depth of tread over 80% of the tyre all the way around.

As for modern tyres with few grooves... hmm...!

Bweemer

Original Poster:

25 posts

260 months

Wednesday 23rd June 2004
quotequote all
bsdnazz said:
I thought the requirement was 1.6 mm depth of tread over 80% of the tyre all the way around.

As for modern tyres with few grooves... hmm...!


I hope not (and so should Michelin) as these are Cups [url]www.michelinman.com/images/catalog/tires/pilot_sport_cup_large.jpg[/url] which would therefore be illegal I guess

Streetcop

5,907 posts

260 months

Thursday 24th June 2004
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There must be 1.6mm over 3/4 (75%) of the width of the tyre.

bumpkin

158 posts

277 months

Thursday 24th June 2004
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[quote=Bweemer]The tread pattern does not however extend over the whole contact surface of the tyre. quote]

the difference is that road legal tyres must have moulded tread, a slick does not. a rally slick has 15%(i think) of it's surface made up of the same little grooves.

the picture shows moulded tread even on the 'slick' bit. those short grooves are the tread. i don't think there is anything that requires tread to 'do' anything.



Don

28,378 posts

306 months

Thursday 24th June 2004
quotequote all
Bweemer said:
Could someone please clarify for me the laws on tyre tread. I run Michelin Pilot Sport Cups as std, which are road legal as they do have >1.6mm tread depth over 75% of the tread pattern. The tread pattern does not however extend over the whole contact surface of the tyre. What distinguishes this legally from a slick tyre where there is, of course, no tread pattern, so 75% of nothing is nothing - if you see what I mean. I appreciate I'm probably very mis-informed and very thick !


I have been considering changing over to these from regular Michelin Pilot Sport tyres. I don't *have* to use the car in bad weather.

How useless are the Cups in the wet? I realise a wet track day would be almost pointless with them but on dry days I suspect they'd be a bundle of fun...and you can drive to and from the circuit without needing to change tyres!

So. Just how bad are they when it rains?

Bweemer

Original Poster:

25 posts

260 months

Friday 25th June 2004
quotequote all
Don said:

I have been considering changing over to these from regular Michelin Pilot Sport tyres. I don't *have* to use the car in bad weather.

How useless are the Cups in the wet? I realise a wet track day would be almost pointless with them but on dry days I suspect they'd be a bundle of fun...and you can drive to and from the circuit without needing to change tyres!

So. Just how bad are they when it rains?


They're not bad at all. There's been too much made of their poor wet weather performance. Standing water is the problem though. They are fantastic on track, but wear rates can be somewhat high (depending what car/setup you have). Mine tend to last 2 days on track.

mcflurry

9,184 posts

275 months

Friday 25th June 2004
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Streetcop said:
There must be 1.6mm over 3/4 (75%) of the width of the tyre.

The tyres are the only thing between the car and the road. IMHO they should be changed way before 1.6mm

Tonyrec

3,984 posts

277 months

Friday 25th June 2004
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Dont forget, the 3/4 has to be the CENTRAL area.