Mercedes A-Class Forum banner
1 - 20 of 37 Posts

·
Registered
Joined
·
91 Posts
Discussion Starter · #1 ·
Just changing the front tyres to michelin ps4 was on Goodyear is it safe to leave Goodyear on the back as still got 5.5mm of tread
 

·
Registered
Joined
·
5,464 Posts
yep that's not a problem, did the same with my BM once the fronts had gone, ps4 front PZero on the rear now all matching
 

·
Registered
Joined
·
274 Posts
Why are you not putting new Goodyears on? I think the F1 AS3 is a great tyre and a lot cheaper than the Michelins.
 

·
Administrator
Joined
·
4,828 Posts
New/Best Tyres should go on the rears

(but if you've still got 5.5 on the rears, that should be OK, just watch out when they get near 2mm)



 

·
Super Moderator
Joined
·
5,107 Posts
Would the same tyre rule apply to our 4-Matics as they would vary the torque transfer.
 

·
Registered
Joined
·
304 Posts
Would the same tyre rule apply to our 4-Matics as they would vary the torque transfer.
I would love to have a definitive answer on this question. Through a lot of googling, my conclusion was a few mm between tyres wont make much of a difference or, we would all break our 4Matic cars when our front wore lower than the rears. Don't put 18's on the back and 17's on the front though with differing tyre sizes LOL.

There is no way at a silly price per corner you would replace 4no tyres if you got a puncture on one part worn tyre and throw away three decent black circles. I do though have a half worn tyre in my shed just in case from an all four corner tyre change. If nothing else, its somewhere for the shed spiders to hide out in!
 

·
Super Moderator
Joined
·
5,107 Posts
:wink:Over to you veeeight.
 

·
Administrator
Joined
·
4,828 Posts
Hahahaha

They had this problem on the Freelanders, the central VCU (Viscous Coupling Unit) was sensitive to tyres of different diameters, so the recommendation was to fit same diameter tyres, and same aspect ratio tyres.

It will be the same for 4-Matic.

Granted, different makes might make a difference in grip levels, but so will driving on different bits of tarmac etc.

So - same diameter wheels, same aspect ration tyres. Good to go.
 

·
Super Moderator
Joined
·
5,107 Posts
Also about the higher tread depth going on the back of a 4-Matic. Is that still the same. I must admit I just get the new tyres put on the fronts which are usually the first to go.
 

·
Administrator
Joined
·
4,828 Posts
Yes. To avoid inadvertent oversteering in the wet, the new/best/better tyres with more tread depth should always go on the rears.



 

·
Registered
Joined
·
304 Posts
@veeeight :smile: Thanks for the info. I normally get all four as I rotate mid lifecycle but would always have put the new ones on the front if just doing two.

Everyday is a school day.
 

·
Registered
Joined
·
274 Posts
I know the expert advice is to put the new tyres on the rear but I've always strongly disagreed.
The vast majority of drivers will drive more steadily in the rain and will not be cornering any where near fast enough for the rears to lose traction.
What is a far more likely scenario in the rain is needing to stop quickly, like on a motorway with lots of spray etc etc.
In this situation 80-90% of the braking is needed on the front and that's where new tyres will make a big difference.
 

·
Super Moderator
Joined
·
5,107 Posts
I know the expert advice is to put the new tyres on the rear but I've always strongly disagreed.
The vast majority of drivers will drive more steadily in the rain and will not be cornering any where near fast enough for the rears to lose traction.
What is a far more likely scenario in the rain is needing to stop quickly, like on a motorway with lots of spray etc etc.
In this situation 80-90% of the braking is needed on the front and that's where new tyres will make a big difference.

Good point and I entirely agree.
 

·
Administrator
Joined
·
4,828 Posts
Why would you disagree with *all* the tyre manufacturers, RoSPA, etc. ?

I follow your thinking, but in reality - your scenario above goes out of the window, as soon as you have some sort of sideways force.

In a straight line, yes, there is the vague chance that you will remain straight, and your front tyres might be called upon to do most of the braking.

However, in reality, any slight deviation from straight, a small steering angle, a slight sidewind etc. - will definitely cause the rear of the car (if the poorer tyres are fitted at the rear) to swing around.

It doesn't matter if its front wheel drive, rear wheel drive, all wheel drive, time and time again, this has been demonstrated, guaranteed to happen on a wet track or road!


But hey-ho - it's your choice!! :)
 

·
Super Moderator
Joined
·
5,107 Posts
I do have to change my fronts at some point this year. I will keep all the advice onboard. My only issue is that the regular people I use e-Tyres seem to have stopped stocking PS4's.
 

·
Registered
Joined
·
274 Posts
Why would you disagree with *all* the tyre manufacturers, RoSPA, etc. ?

I follow your thinking, but in reality - your scenario above goes out of the window, as soon as you have some sort of sideways force.

In a straight line, yes, there is the vague chance that you will remain straight, and your front tyres might be called upon to do most of the braking.

However, in reality, any slight deviation from straight, a small steering angle, a slight sidewind etc. - will definitely cause the rear of the car (if the poorer tyres are fitted at the rear) to swing around.

It doesn't matter if its front wheel drive, rear wheel drive, all wheel drive, time and time again, this has been demonstrated, guaranteed to happen on a wet track or road!


But hey-ho - it's your choice!! :)
I think your third sentence is somewhat far from reality. So any slight deviation from going in a straight line will cause the back end to lose traction?? So nobody successfully goes round a corner on a wet road?
If the rear tyres have legal tread on them they will still grip round a corner at normal speeds unless you are driving far too fast for the conditions.
The point is a driver is able to stop that happening by just not driving too fast in the wet. But sudden unpredicted extra braking can be needed even at normal wet speeds, and the driver isn't controlling when that occurs, and in that situation better grip on the front will surely help more? When tyres are reviewed they compare braking distances on a wet road, not slip angles on the rear tyres...
I think the experts are just covering themselves in a worst case scenario, just as most do nowadays in this H&S conscious world. The average driver is more likely to lose control of a car if the rear slides than if the car doesn't stop very quickly, so that's probably behind their thinking, even though I'm sure the likelihood of it happening is very small in comparison.
But like you say, it's down to choice!...
 

·
Administrator
Joined
·
4,828 Posts
In one sentence ...

When braking - the rear of the car goes light, if your front is grippier than your rear, your rear will lose grip and *will* come around (provided there is the smallest of sideways influence).

I know, I know, we’ve had enough of ‘experts’ lol


:)
 

·
Super Moderator
Joined
·
5,107 Posts
Not had enough of experts at all!!!

Too many thick people running things.
 

·
Registered
Joined
·
211 Posts
Very funny arguments here from the new-tire-front-group, it's fun to read...:wink: New tires belong to the rear, always!
You can cheat yourself, but not physics... :smile:
 

·
Super Moderator
Joined
·
5,107 Posts
Can people be very careful when being redirected off the Michelin website to a retailer.

I put in MICHELIN PILOT SPORT 4 235/40ZR18 95Y for my car. Then the post code and it came up with the retailers in my area which had it. So I went to the Kwik Fit site which was over £21 per tyre cheaper than E-Tyres, who now have the tyre back in stock.

I ordered and paid and the e-mail came back but the ZR was missing. It was not the tyre as the Michelin link would lead you to believe. I have cancelled the order and contacted the customer care number on the Michelin site but the bloke at the other end was deliberately being dim and saying it was nothing to do with Michelin.

I think what you pay for is what you get so watch out for something which seems too good to be true. It usually is.
 
1 - 20 of 37 Posts
Top