Do I have the wrong tires on?

[gIzzE]

I have to say I agree with AkisGr on this.

People are saying the difference between rolling radius is far too high, being some 24mm different. However, Mercedes oem set up and the correct tyre sizes are also not a matched rolling radius, they are also out by 20mm, an extra 4mm will be fine, you can get more difference between worn tyres on different axles.


What tyres are they? How old are they?

The date they were made can be found here....

If they are older than 4-5 years they have probably gone hard which makes them feel awful.

If it were me I would look at a Dunlop EffcientGrip, the quietest and most comfy tyre I have ever used.





Rear, 275/40/R19
Front 255/40/R19

 

[markjay]

I have to say I agree with AkisGr on this.

People are saying the difference between rolling radius is far too high, being some 24mm different. However, Mercedes oem set up and the correct tyre sizes are also not a matched rolling radius, they are also out by 20mm, an extra 4mm will be fine, you can get more difference between worn tyres on different axles.


What tyres are they? How old are they?

The date they were made can be found here....

If they are older than 4-5 years they have probably gone hard which makes them feel awful.

If it were me I would look at a Dunlop EffcientGrip, the quietest and most comfy tyre I have ever used.





Rear, 275/40/R19
Front 255/40/R19

There is no need for the front wheels to have the same diameter as the rear ones. As anyone driving a tractor can testify

There is a need however (to my mind anyway) to maintain the same diameter as the original MB fitments, or any other size listed by MB in the owners manual.

The issue is that fitting tyres of sizes not recommended by the manufacturer means that you are in your own territory now as any R&D or chassis tuning carried out by the manufacturer for the official tyre sizes will no longer apply once you deviate from the manufacturer's recommendations.

Whether the actual effect will be significant, unnoticeable, or non-existent is another matter.

On another note, there are potential insurance implications for running unapproved-sized tyres on your car, at the very least you should declare this as modification, but even so this may not cover you in case of serious accident and the insurer could claim your is policy void.

 

[gIzzE]

I agree, I would swap as soon as I could, but I wouldn't say he has to get them off asap or his car will throw a wobbly with the abs system and throw him into a ditch.

There is less than 4mm difference between recommended diameter and actual diameter, you can get more than that with the 'recommended' winter tyres.

I tend to go down in size myself anyway, no need for a 275 wide tyres on that sort of car.
If it were me, I would consider sticking the 255 on the rear and sticking a 235 on the front, but that is a whole new bag of confusion.

 

[MBScoob]

All other issues aside, I expect 19's will always give a fairly harsh ride when paired with "sports" suspension, depending what you're used to. I'm on 18's myself and they feel fine to me, but my other car is VERY firmly sprung, so it's all relative. I did however run a set of MB 16's while my wheels were being refurbished and the ride quality was sublime. Tyres were narrower with a much higher aspect ratio, of course. Where the car did suffer was with cornering, where the additional tyre roll due to the higher profile meant the car felt far less planted during cornering - I'd certainly not want to hustle the car around corners as I would with the 18's.

Regarding the slight size discrepancy, I'd not expect that to contribute to the ride quality in any noticeable way, unless you're particularly sensitive to such things. Tyre pressures however can make a world of difference, so that part of your question is very relevant. My car has the pressures for the various (standard) tyre option printed in the fuel filler cap, I assume this is the MB standard?

I've had cars to which I've fitted non-standard sized tyres to and, generally, you can retain the same pressures in my experience. Personally, as I run exclusively "XL" reinforced tyre wall tyres, I've always added a couple of extra psi as this gives me the best performance from the tyres. Very subjective of course as some might prefer the firmer ride and improved feedback a slightly higher pressure provides, while others may well prefer the additional comfort of a standard, or indeed slightly lower pressure. Always worth keeping an eye on tyre wear of course, as you could see premature wear due to under/over inflation - which, again, may be worth the cost to get your preferred ride quality. Oh, on my cars with XL's where I run higher than standard pressure, I'm yet to see anything other than even tyre wear.

It may well be that even with the MB standard tyre sizes fitted, running at the recommended pressures you still find things a little firm, if that's the case dropping a wheel size or two and having proportionally higher profile (but same rolling diameter) tyres might help, though cornering might suffer.

Hopefully this has been of use.

Scoob.

 

[C43AMG]

I have 8.5 x 19 Front & 9.5 x19 Rear 0n the CL

245/40/19 " 275/35/19 "

 

[Peter103]

Could he put 255x45's on the front? Or have I missed something?