when to replace tyres

[dave]

Ive seen a few threads now where people seen to think that tyres with 4mm of tread left are only half way through there life. infact 4mm is almost 90% worn or fully worn for winter tyres.

the uk legal limit maybe as low as 1.8mm but tyres wil have severely reduced grip and greatly increased stopping distance when they reach 3mm, especially in the wet.

Therefore you should be replacing your tyres when they reach 3mm or 4mm for winter tyres.

 

[Giacosa]

Ive seen a few threads now where people seen to think that tyres with 4mm of tread left are only half way through there life. infact 4mm is almost 90% worn or fully worn for winter tyres.

the uk legal limit maybe as low as 1.8mm but tyres wil have severely reduced grip and greatly increased stopping distance when they reach 3mm, especially in the wet.

Therefore you should be replacing your tyres when they reach 3mm or 4mm for winter tyres.

This is my chance to ask something about tyres I have never understood. I can understand why a tyre has less grip in wet or snowy conditions with less tread. But why would a tyre with say 2mm of tread have less mechanical grip in the dry than a tyre with 4mm. The tread pattern hasnt changed and the amount of tyre in contact with the road presumably hasn't changed so whats the mechanism that gives less grip?

 

[jrkitching]

..why would a tyre with say 2mm of tread have less mechanical grip in the dry than a tyre with 4mm. The tread pattern hasnt changed and the amount of tyre in contact with the road presumably hasn't changed so whats the mechanism that gives less grip?

I'm not at all sure that it would. The tread pattern is there to dispel water and if the road surface is bone dry then you will actually get more grip from slick tyres, after all, that's what the racing folks use.

Wet performance is completely different and you only have to watch a race after the rain starts & before everyone's made it to the pits for a tyre change to see the effect of this.

Another good reason for changing tyres early is that they are more vulnerable to puncture damage as wear approaches the legal limit.