Hey folks, quick question. I'm at 12,500 miles and just had a flat rear left tire (PS4S). I have the wheel+tire protection. When I went into the dealership, they said the rear tires looked practically new and said I could just replace the one tire.

I checked the tire tread myself across the 4 main grooves and these are the measurements I got for each tire. Each number is /32 and starts from the outer grooves and goes in on the four main grooves.

RL: 8 8 9 9 8
RR: 6 7 8 8 6

I haven't noticed anything while driving, but given that our cars have the rear LSD and the 4Matic+ system, I was wondering if this is fine or if I should go back to the dealer and get a new RR tire asap. If I do need to change it but it's not urgent, I have to go back in for Service B in 30 days anyway and wondering if it's ok to keep driving the car until then. Neither the manual nor the AMG supplement say anything about this.

What do you all think?

 

TO me fine...

Rolling radius depends on tire OD of course but also air pressure and tire load since it not round with weight on it as bottom is squished a bit.

Since this is so minor if anything you might possibly feel the car want to pull to one side but I doubt it.

IF worried lower pressure on the new tire a few PSI versus old tire

 

I'd rock that it's fine., Had the same issue happen to me - screw in a rear tire, only replaced one, all is fine.

 

I agree it will be fine, but I must point out that the Pilot Sport S 5 is such a superior tire that, if it were me, I'd probably use this opportunity to upgrade. Especially if your fronts have 12,500 miles on them, they're probably getting low and I can't think of another "mod" that would improve the drivability of the car for that amount of money. The biggest difference is noise level. That infernal droning of the PS4S is so greatly reduced that it feels like a new car. Handling is improved as well.

 

I would really check the inner corner of the tire near the sidewall. The rear has camber and the tires wear there first. My tires looked fine across the width of the tire and I thought I had another 10,000 miles of wear left on them when my pressure started going down on one of the tires. Thought I picked up a nail. Used the pump to bring the pressure back up and then limped a mile or so away to a nearby discount tire shop. They came out and looked and showed me that the inner edge of both rear tires were down to the cords and that's where the leak was coming from. Said it was really common on European sports sedans.

Called Mercedes and they arranged for a flatbed tow truck to bring the car to my dealer for a new set of PS5s. Tow truck driver said the same thing, he tows Euro sedans for the same issue all the time.

Can't really see the problem standing next to the car or looking at it from the rear. Need to bend down and look under the car closely at the inner edge of the tires.

Worn rear tire inner edge
New PS5 for comparison

 

i just went through this on a front tire on my E53. tires were balder than yours but 5-6/32. common "knowledge" said to replace all four since tread depth is different, but that appears to be an old wives tale on the 4matic/4matic+ and more for cars like an evo or subie. i calculated the rolling circumference difference and it was under 2%. i read all kinds of stuff how the limit is 2.5-3% but i couldn't find an actual merc source to corroborate it, seems to just be on forums and tire shops and possibly related to some old manual from a long time ago

finally tried my dealer/SA who is technically knowledgeable and he told me it's not a problem at all and you can replace one and 4matic will not care. i elected to replace both fronts with the same tire as on the rears (DWS06+) and keep the loose good tire for a backup. it drives great. in 5-8k miles i'll probably just swap the rears as a pair and call it a day

this is only my personal opinion but i wouldn't want mismatched tires just due to treadwear differences (though I would guess the PS4 vs PS5 is marginal) though to your original question i can't imagine it would actually cause or accelerate a mechanical issue when we are talking about like 0.25% or so rolling circumference. not sure how the LSD would affect that in your 63 models

 

Do dealers check alignment for less than a full alignment?

 

That is what happened to me on my passenger right front tire. Tires look great and the inside was smoked. My only saving grace was I bought a forged set of rims that came with pretty new tires, and when I went to change them I saw how bad that tire was.

 

Thanks everyone for the helpful replies. I haven't noticed any pulling or binding or anything since the change and after reading the replies here I'm confident I'll be OK until the next tire change. I got down and looked at the inside of every tire and didn't see major wear or damage there either but I'll keep an eye on them.

I actually got both fronts replaced last year after a nail in one tire; the same-day service advisor at the time was different to my usual guy and measured the fronts at 5 or 6/32 so I ended up changing them both.

Been hearing a lot of good things about the Pilot Sport S5s, I think those will be my next tire whenever I get the opportunity!

 

Reality is today’s models - excess edge wear…. it’s not a tire brand issue !

Often quoted reassuring “Will Carry Out a Full Front and Rear ‘4’ Wheel Alignment”.

Is now only basic Toe - directional adjustment (new car industry’s best kept secret).

Cost savings and ever increasing speed of new car assembly lines Front Camber and Caster along with Rear Camber has been deleted. Even on AMG Performance models.

Onus has been put back on owners to fund costly, premature tire replacement !

Now a compromise of one setting. No ongoing adjustment to cater for high cambered roads with excess passenger side edge wear. Altered height through load carrying or lowering with excess inner edge wear both sides. Performance driving and excess outer edge wear. No adjustment to cater for curb knocks !

We saw the need and manufacture “BOLT-ON” kits - no special tools required or time consuming control arm removal (and also replacing at same time the 4 Front and Rear highest wearing suspension bushings).

Adjustment - Unique K-MAC Patented design allows precise easily accessible single wrench . Ultimate - direct on alignment rack UNDER LOAD !

SEE SPOILER





AUDI to VOLVO - K-MAC Experience Of Resolving OEM Suspension Shortcomings (and Costs) Since 1964 !