I have acquired a set of wheels with tyres. The tyres are dated Dec 2016. Tread depth is 3 -5 mm with one at 6 mm. The more worn tyres are showing 'micro ' cracks at the bottom of the drainage channels. Sidewalls are perfect and tread blocks look fine on the surface. I am not sure what would have caused the 'micro' cracks as I assume it cannot be aging ( less than 4 years old ). More importantly is this a safety issue? Since these are for a Porsche Cayman I will take no chances in terms of 'performance' use but are they good enough to run around before I get new replacements. Please advise.

A friend of a cousin has used tyres with generalized cracks all over.
I donīt condone the use of such, but more often than not, tyres failed on other causes, puncture by hitting a pothole or by a nail/screw.
As long as your driving habits take into consideration that they may fail without notice, I think the friend of my cousin is OK.
Here in Mexico there are no laws regarding the condition that your tyres must be.
We also donīt have any liability issues for accidents that occurred because of those conditions.
Is that good or bad?
Not sure, but it is just the way it is.
AA

With the current world problems, a few cracks wont do to much, plus soon, you will not be allowed outside, just don't go to far or fast

But in the real they would be an MOT failure, and so could also be a Police flag of an unsafe tyre, and 3 points plus a fine

steve

That's 3 points on your licence and a fine for each tyre

Hard to judge without pictures of the cracks

Take one to your MOT station and ask them.

Pretty sure perishing/cracking is only an advisory on MOT test.

What brand are they?

As Above

Unless their really bad I'd be surprised if they were an MOT failure (potential advisory only)

Having said that their going onto a performance car, so worth getting a second opinion

I've had this on similar age tyre from Michelin and from Continental. All the tyres were of similar age to yours and had not covered great mileages, the Michelins were the tyre fitted from new!
In both cases I replaced with new (Goodyear and Dunlop) tyres. I asked the dealer to send the tyres back to the manufactuers and in both cases got a refund on the new tyres, 60% on the michelins and 70% on the Continentals even though I had fitted other brand tyres.
My wife recently bought a DS3 which came with two new Michelin tyres on it. The date stamp indicates 4 years old but one of the two is cracking already. I'm going to start a conversation with Michelin as this is totally unacceptable for a tyre with only 500 miles travelled. Given my last experiences the new Uniroyals will be at least partially paid for.

I have just sold a 2014 Ford Ranger. It still had 2 original tyres, 110,000 km on them.
I drove most of them. Front Brake pads had 50% life on them. Original from new pads (never replaced)
I drove that thing like a grandma...
At the speeds I drove that thing even a catastrophic tyre failure would not have caused an accident.
One thing is legal requirements and safety margin.
3 mm may be legal (or 5, I donīt know), but if you are pushing the limits with your driving habits, it may be outright dangerous.

I have cracks appearing on tyres after just one year, depends on the quality and if they have been overheated or under inflated. You don't say what make they are either, is this a case of budget tyres on an expensive car? Not an MOT failure till you can see the chords but being restrained in a Porsche that will be the day.

Plenty of cracks in my tyres over the years. None through to the fabric, which (like cuts) are where the risk lies. Been through dozens of MOTs no problem.

The only tyres I've had fail showed no outward signs of damage

[Edited on 20/3/20 by coyoteboy]

For information the tyres are Goodyear Eagle F1 ZR and Porsche N0 rated. No idea if they are original fit but could be.

A quick google yields literally dozens of people complaining of the same thing.

Also pops up a few bulletins that suggest moving a vehicle with a summer-only tyre in temps around -7 or less, can result in cracking.

[Edited on 20/3/20 by coyoteboy]

Yip the good old days of classic car shows out would come the sticky can of flexible tyre paint to hide a multitude sins, cracks, cuts, glued in bits factory fresh in minutes

If they're not going to be used for long or at high speeds/cornering loads then they will be absolutely fine. Simple test is to whack them up to around 60psi & drive a few miles on them, if they survive that they aren't going to give a problem at normal pressures & loads.
Never seen an MoT fail on cracks within the tread, nor seen a failure that I could attribute to that - I very much doubt the damage extends into the carcass

Thanks Russ, you have put my mind at rest. I could not resist a set of near perfect Porsche (18 inch ) wheels for Ģ200! I will replace the tyres soon as the 20 inch wheels/tyres on the car are a joke - triumph of style over function. (By the way you have to be 75 years old to win a Cayman as a pressie - hope you are well )
J

I'm fine thanks John, good to see you are too, never had you down as a Gay man tho???