Ideal tread depth for replacement?

[Slartibartfast]

I know minimum legal tread depth is 1.6mm but what is "ideal" depth for replacements do you think? I don't want to wait until barely legal but I also don't want to be replacing when there's enough tread for reasonable performance. These days my driving style is "comfort" rather than "performance". Car is S Class W221 S350L with 20" Alloys (Michelin Sport 4s)

 

[ChrisHGTV]

I know minimum legal tread depth is 1.6mm but what is "ideal" depth for replacements do you think? I don't want to wait until barely legal but I also don't want to be replacing when there's enough tread for reasonable performance. These days my driving style is "comfort" rather than "performance". Car is S Class W221 S350L with 20" Alloys (Michelin Sport 4s)

I normally do mine at between 3 and 4mm (im just replacing mine at 4mm now). I had a terrible drive in the wet once in my old Mondeo - they were just over 2mm and the aquaplaning was really bad. It was very wet to be fair, but these were GoodYear Eagle F1 Assym 3 so decent tyres. I ended up driving back from Dorset at 50mph. So now it's 3mm min for me.

 

[Germgh0st]

Same here, somwehere between 3 and 4mm generally. You can tell when the tyres start to 'drop off', especially in bad weather.

 

[BTB 500]

These days my driving style is "comfort" rather than "performance".

It's largely going to be down to wet braking performance then, but the interesting bit is that this varies a fair bit from one brand/type to another anyway. A tyre rated ‘A’ for wet grip will stop 18 metres shorter from 50 mph in the wet than one with an ‘E’ rating. So a well worn tyre may potentially outperform a brand new one, depending on the make/model!

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Of course for dry grip you want as little tread as possible (e.g. slicks)

 

[BigJase88]

Generally anything below 3.0mm gets a bit sketchy in the wet. Below this depth on a motorway in wet weather gets the bum twitching a bit at times

 

[MikeInWimbledon]

Agree with all the above. I'd replace before the tyres get down to 3mm. (Or eight years old)

Being the sad soul that I am, I tend to overanalyse it and replace earlier if it's Autumn, but not so early if it's Spring.

 

[190]

I'm currently at 4mm rear and 5.5 mm front so won't be changing them just yet. I'll probably run one axle down to 2 - 3 mm and then change all 4. That might involve another front to back tyre rotation, they have already been rotated once.

 

[Slartibartfast]

I'm currently at 4mm rear and 5.5 mm front so won't be changing them just yet. I'll probably run one axle down to 2 - 3 mm and then change all 4. That might involve another front to back tyre rotation, they have already been rotated once.

I can't rotate mine as different sizes front and rear

 

[Will]

Change them at 4-5mm and sell the old ones on eBay!

 

[ALFAitalia]

Can your see the canvas?....no?.....well in that case there is at least another ten thousand miles left in them!

More seriously I think it depends how your use your car....if it's used all year round in all weather's then you might want to change your tyres rather sooner than if you have a classic Merc or an SL or similar that is just used as a high days and holidays toy that never sees rain on which you could happily take the tyres down to close to the 1.6 mm limit with no safety concerns....in fact as long as they have not hardened with time you will get more rubber on the road and more grip in the dry as they wear down.....tread is only there to disperse the surface water.

 

[leef44]

3mm is the limit for me to change. My concern is aquaplaning.

 

[Bobby Dazzler]

if it's used all year round in all weather's then you might want to change your tyres rather sooner than if you have a classic Merc or an SL or similar that is just used as a high days and holidays toy that never sees rain on which you could happily take the tyres down to close to the 1.6 mm limit with no safety concerns....in fact as long as they have not hardened with time you will get more rubber on the road and more grip in the dry as they wear down.....tread is only there to disperse the surface water.

When you check the MOT history of mid-life sporty cars which cover low annual mileages, it’s surprisingly common how many fail due to tyre tread depth. I suspect it’s for this reason - occasional use on warm dry days, and driven with gusto.

 

[ALFAitalia]

Tyres are one of the most common MOT fails.....and about the easiest thing to check.....just look at them and its pretty obvious even if you a not mechanically minded!! I never understand people who let their cars fail on tyres (unless its perhaps got a bulge on the inside tyre wall...but that's quite rare).

 

[BTB 500]

I never understand people who let their cars fail on tyres (unless its perhaps got a bulge on the inside tyre wall...but that's quite rare).

Asymmetric wear is more likely - I've had a rear tyre badly worn on the inside part of the tread but looking OK on the outside. Dealer spotted that while it was up on the ramp and (rightly) put the spare on before doing a road test.

 

[TC350]

Another in favour of an absolute minimum of 3mm here. Being the only thing that connects my car to the road means I'm not going to take any chances. I change all four tyres at the same time so invariably the rears still have 5mm left, but I didn't buy a Mercedes for cheap motoring!

 

[Charliecloud]

3mm for me, MB put a note on my Inspection sheet when it went in for rear subframe Inspection.

 

[BTB 500]

Another in favour of an absolute minimum of 3mm here. Being the only thing that connects my car to the road means I'm not going to take any chances.

As mentioned the wet grip rating is also important. If you don't want to take any chances you should only buy A rated tyres ... many premium brand ones (e.g. from Pirelli/Continental/Dunlop/Michelin/Goodyear/Bridgestone) are B rated.

 

[TC350]

As mentioned the wet grip rating is also important. If you don't want to take any chances you should only buy A rated tyres ... many premium brand ones (e.g. from Pirelli/Continental/Dunlop/Michelin/Goodyear/Bridgestone) are B rated.

Indeed. I have Pirelli All Season on now.

 

[BTB 500]

Indeed. I have Pirelli All Season on now.

Some of those are only B rated for wet grip though (certainly Cinturato All Season Plus and Cinturato All Season SF 2).

 

[TC350]

Some of those are only B rated for wet grip though (certainly Cinturato All Season Plus and Cinturato All Season SF 2).

Unfortunately the better wet rated all season tyres weren’t available in the size I needed for the rear when I bought them. But they’ve still felt great so far, even in the recent heavy rains.