At what tread depth to replace tyres?

[TripleS]

So why is there not a more vocal campaign to increase the permitted minimum tread depth to be increased? How have the authorities decided to impose a requirement for ESP systems, but not to increase the minimum tread depth to 3 mm?

Presumably they feel there is no justification for requiring an increase in the minimum tread depth, and I suspect that's the right decision. I wonder how many mishaps are caused because drivers have only 1.6 mm of tread rather than 3 mm? Very few, probably.

Best wishes all,
Dave.

[TripleS]

So why is there not a more vocal campaign to increase the permitted minimum tread depth to be increased? How have the authorities decided to impose a requirement for ESP systems, but not to increase the minimum tread depth to 3 mm?

PS Personally, my ideal is to do a track or handling day once the tyres get to 3mm, and to get value out of the rest of the tread that way.

Good idea, for your purposes; but there again it's not going to be an option that many people would go for. I know I wouldn't, partly because I'm not willing to subject my car to that sort of treatment.

Best wishes all,
Dave.

[TripleS]

The difference in tyre cost between replacement at 1.6mm vs 3mm is not a great deal if I remember correctly.

Really? Assuming that a new tyre has 8mm of tread, and that the wear rate (as in mm of tread lost per mile travelled) is constant, then I make changing tyres at 3mm rather than 1.6mm to be a 28% cost increase - which I'd regard as quite a lot.

I think the first assumption is valid, if not a little conservative - 8mm is about the maximum I've measured for the tread depth of a new tyre. The second assumption may be open to challenge though.

What price do you place on safety?

A reasonable one? Lots of things involve a compromise between cost and benefit, and the search for safety is no exception.

Best wishes all,
Dave.

[TripleS]

Even 1 mm of tread worn away on a new tyre increases the stopping distance on smooth concrete significantly - perhaps we should all change our tyres a lot earlier than 3mm?

Or perhaps we shouldn't be using concrete for road surfaces?

A nice smooth tarmac surface with reasonable grip and quiet running characteristics for me, please.

Best wishes all,
Dave.

[WhoseGeneration]

Tyres?
What about all the other wearing areas of our cars?
Presumably a car is only fully functional for a short period?
Tyres, I go with 3mm.
That though, doesn't provide the same performance as 8mm.
Your dampers?, ever had them properly checked?
No, neither have I.
MOT testers only look for evidence of leaking and the "bounce test" is not really useful these days because of the spring rates of many cars.

[Garrison]

I think it is down to your judgement call really.

On the Merc I rotate tyres every 5k and the whole set needs to be at 10k with about 1.6 - 2.5mm left on the tyres. However, as I do 10k a year in it and the change is always in June (less rain and hot summer), I don't mind running it closer to the legal limit.

On the MR2, it was just over 3mm in mid November. As it is mid-engine, rear-drive and no traction control, I decided to get them change anyway in anticipation of the rain, snow and ice.

Hope this make sense.

Garrison