tyre tread - what's the limit?

Have a look here:

HTH

Chris

In round terms the legal minimum is 1.6mm over 75 percent of the tyre, the rest of the tyre tread area must have 'visible' tread ie not bald, nor have any cords exposed.

Safety wise anything under 3 mm over the whole width makes a massive difference in the wet, particularly on stopping distances. in dry conditions there is very little difference between bald and new.

mrcheerful

To clarify that, that is the centre 75% of the width of the tyre around the entire circumference.

Bald tyres could even be better in the dry. Apart from that I agree, the

1.6mm depth is a joke in terms of safety, even 2mm has a significant difference.

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It wasn't that long ago the limit was 1mm, raised to 1.4 then the current

1.6mm IIRC.

It's still 1mm for motorcycles as well I think.

neutron (neutron(abcde)@f.off.com) gurgled happily, sounding much like they were saying :

Irrelevant. That's well overdue for changing, especially in the current weather.

[Snipped Text]

It was never 1.4mm, it was 1mm, but that was over the entire width of the tread. It was set to 1.6mm well back into the 80's.

Yes. However, a bike doesn't suffer with aquaplaning, and I usually find I need to replace a tyre long before it gets to 1mm as the handling gets crap as the profile changes.

It's 1.6mm, but I feel twitchy with less than 3mm dry and 6mm wet. I like to change my tyres early.

-- Stuart

Mmm, I've never felt that less tread depth makes a difference in the dry, in theory the grip should be better because of less tread shuffle, but then there are a lot of variables such as age of rubber etc. But you are surely not saying that you change your tyres at 6mm for wet grip?

The question is, when should you change your tyres, as anything less than the new tread will be sub-optimal in the wet?

Biggles

Legal limit is 1.6 mm - but 2mm is far enough.

There are rules about the comparison between 2 tyres on the same axle - I think its a difference of 4mm for cars, but 2mm for 4 x 4's

[...]

Would you post a link to this info if you have one please?

Chris

The message from Chris Whelan contains these words:

Here are two links everyone could do with bookmarking...

Nonsense. There is no such rule.

-- Dave Baker

Guy King wrote on Sat, 12 Nov 2005 16:56:16 GMT:

Which has nothing to do with the non-existant rule being asked about..

mrcheerful . wrote on Fri, 11 Nov 2005 12:26:09 GMT:

According to

"Note: Each side of the central band of the tyre can be devoid of tread (ie. 'bald') and still meet the pass standard although in practice such tyre wear is, unlikely to occur."

Why the need for visible tread?

[...]

Because once the tread is gone it's the structure of the tyre carcase that's being worn.

A

[...]

I replace at 3mm and always in axle pairs.

It's unwise to run mismatched tyres on the same axle.

A

The message from "David Taylor" contains these words:

Exactly why I posted it! Though I must admit to having forgotten to say "Neither of these mention it".

Still 1mm for trucks and busses too, god only knows why!