MB E250 CDi AMG Saloon Tyres Sizes Conundrum

[LGGVW]

Hi Everyone,

I wonder what the knowledgeable fellow MB aficionados think, if I may...

The tyres actually installed in my MB E250 CDi Saloon (W212 Facelift) are:

• Front Axle: 245/40 R18 97Y
• Rear Axle: 265/35 R18 97Y

I am not particularly thrilled about different tyre sizes, so I looked up the Owners Manual, which says something different:

• Both Axles: 245/40 R18 97Y (Estate only)
• Front Axle: 245/40 R18 97Y (Saloon)
• Rear Axle: 265/35 R18 97Y (Saloon)

But Winter/All Season Tyres is different:

• Both Axles: 245/40 R18 97Y (Estate and Saloon)

Given the above, I reckon I should be okay to fit all 4 tyres the same size, ie., 245/40 R18 97Y, regardless of whether they are Summer or All-Season tyres, right?

Any views out there most welcome.

Thank you

Best regards

 

[markjay]

Based on the data posted above, the answer is yes.

That been said, it seems that (according to the above) MB only made available your car with same-size front and rear wheels on the Estate model, so strictly-speaking it could be argued that this isn't 'to manufacturer's original spec' because your car is a saloon - I suggest that you run this (the new wheel/tyre sizes at the rear) by your insurer and see what they say.

 

[TeddyRuxpin]

I am not particularly thrilled about different tyre sizes

…what? Why?

 

[clk320x]

Hi Everyone,

I wonder what the knowledgeable fellow MB aficionados think, if I may...

The tyres actually installed in my MB E250 CDi Saloon (W212 Facelift) are:

• Front Axle: 245/40 R18 97Y
• Rear Axle: 265/35 R18 97Y

I am not particularly thrilled about different tyre sizes, so I looked up the Owners Manual, which says something different:

• Both Axles: 245/40 R18 97Y (Estate only)
• Front Axle: 245/40 R18 97Y (Saloon)
• Rear Axle: 265/35 R18 97Y (Saloon)

But Winter/All Season Tyres is different:

• Both Axles: 245/40 R18 97Y (Estate and Saloon)

Given the above, I reckon I should be okay to fit all 4 tyres the same size, ie., 245/40 R18 97Y, regardless of whether they are Summer or All-Season tyres, right?

Any views out there most welcome.

Thank you

Best regards

The rear wheels are 9J and front wheels are 8.5J… hence needing 265 (wider) tyres on the rear compared to the 245 on front… why on earth would you want to fit 245 all round?

 

[markjay]

Personally, I've always preferred to have the same size tyres on both axles.

This is because I rotate the tryes front-to-rear at every service, to maximise tyre life, then change them in sets of 4. This way I always have 4 identified tyres with similar wear.

The price to pay is visual, and I do appreciate that wider rear tyres make the car look better. In terms of performance, the way I drive, the width of the rear tyres will make no difference........

 

[TeddyRuxpin]

The wheels are different sizes as @clk320x mentioned

Even an E250 CDI has what… almost 500nm of torque?

I’d trust the Mercedes engineers

 

[colinallcars]

Personally, I've always preferred to have the same size tyres on both axles.

This is because I rotate the tryes front-to-rear at every service, to maximise tyre life, then change them in sets of 4. This way I always have 4 identified tyres with similar wear.

The price to pay is visual, and I do appreciate that wider rear tyres make the car look better. In terms of performance, the way I drive, the width of the rear tyres will make no difference........

But what about the different wheel sizes?

 

[markjay]

But what about the different wheel sizes?

I meant to say that when looking to buy a car, I would prefer to opt for a trim level that does not have wider rear wheels.

If you've already got a car with wider rear wheels, then obviously the only way of achieving 4 identical tyres is by replacing the rear rims with narrower ones.

 

[st13phil]

The manual lists not just the permissible tyre sizes, but also the permissible tyre size / rim size combinations.

If the desired tyre size on both axles is listed as a permissible tyre size / rim size combination, the OP's good to go - but beware combinations that are only listed as valid for winter fitment, and also be aware that a taller, narrower, tyre on the rear wheels will look "stretched" and will leave the rim edge more exposed to kerbing damage.

 

[markjay]

The manual lists not just the permissible tyre sizes, but also the permissible tyre size / rim size combinations.

If the desired tyre size on both axles is listed as a permissible tyre size / rim size combination, the OP's good to go - but beware combinations that are only listed as valid for winter fitment, and also be aware that a taller, narrower, tyre on the rear wheels will look "stretched" and will leave the rim edge more exposed to kerbing damage.

I think the potential issue here is that if ignoring the winter tyres size, then the desired combination is only listed for the Estate, while the OP's car is a saloon.

 

[colinallcars]

The manual lists not just the permissible tyre sizes, but also the permissible tyre size / rim size combinations.

If the desired tyre size on both axles is listed as a permissible tyre size / rim size combination, the OP's good to go - but beware combinations that are only listed as valid for winter fitment, and also be aware that a taller, narrower, tyre on the rear wheels will look "stretched" and will leave the rim edge more exposed to kerbing damage.

The OP makes no mention of wheels sizes. I wonder if he is aware they are possibly (probably) different as he seems to be focused on tyre sizes.

 

[LGGVW]

…what? Why?

Primarily because from what I gathered so far from shopping online, the offer in all-season 265/35/R18 is utterly miserable. Almost nothing bar Michelin, which in turn has inflated (no pun intended) the prices, given the scarcity in that size 265/35/R18 from competing manufacturers.

It follows that keeping that size for the rear axle will add almost £300 to the overall cost of 4 tyres plus fitting. Outrageous to say the least; not because of £300 per see, but because of abusive profiteering by Michelin.

Thus, I either cough up the extra £300, playing the exploitative game Michelin is playing, if I wish to fit all-season tyres, or go for Summer tyres, keeping to break-in-wet class A, and maybe fuel savings class B or C.​

 

[LGGVW]

The rear wheels are 9J and front wheels are 8.5J… hence needing 265 (wider) tyres on the rear compared to the 245 on front… why on earth would you want to fit 245 all round?

I'm not sure I follow, apologies ... What are these 8.5J front and 9J rear? I am not familiar with these values. All wheels are R18, so I am assuming the alloys are exactly the same all around.

 

[st13phil]

What are these 8.5J front and 9J rear? I am not familiar with these values.

The wheel widths - which is highly relevant.

All wheels are R18, so I am assuming the alloys are exactly the same all around.

Almost certainly a wrong assumption, I'm afraid. Most Mercedes RWD cars have what's known as a "staggered" wheel setup, with wider tyres and wheels at the rear than at the front.

 

[LGGVW]

But what about the different wheel sizes?

I do trust Mercedes Engineering, but if they approve the same tyre size for Winter tyres/both axles, ie. 245/40/R18, then it should follow that the actual alloy wheel size is either the same or the difference is too small to matter that much?

 

[Chrishazle]

I'm not sure I follow, apologies ... What are these 8.5J front and 9J rear? I am not familiar with these values. All wheels are R18, so I am assuming the alloys are exactly the same all around.

If you take one of each wheel off and look on the inside of the spokes, you will find an MB part number starting something like A211... plus the full description of the rim size, namely:
7.5J or 8J etc - this is the width of the rim in inches and the shape(J) - x18, which is the rim diammeter in inches.
ETxx- this is the rim offset in mm, and is the offset of the hub of the rim from the centre of the rim, important for clearance over calipers when fitting the rim and for the tyres not to rub on the wheel arches.
As said above, a staggered setup is common on MB cars - I have it on both of mine, with 17" rims on both but 7.5J fronts and 8J rears. I can run 245/40 rear and 225/45 fronts, but Blobcat on here has an identical car to my SLK and runs 225/45 all round for winter, but as mentioned you loose rim protection so have to be even more careful not to kerb the rims.

 

[markjay]

I do trust Mercedes Engineering, but if they approve the same tyre size for Winter tyres/both axles, ie. 245/40/R18, then it should follow that the actual alloy wheel size is either the same or the difference is too small to matter that much?

The manual should give both the tyre size and rim diameter, as well the rim width (e.g. 8J or 8.5J etc).

Also, if you look at the official accessories list for your car, you'll see that MB specify the width (and ET) for each wheel option:

More Mercedes - Technical Accessories and Collection Products from Mercedes-Benz

More Mercedes - Technical Accessories and Collection Products from Mercedes-Benz

accessories.mercedes-benz.com

More Mercedes - Technical Accessories and Collection Products from Mercedes-Benz

More Mercedes - Technical Accessories and Collection Products from Mercedes-Benz

accessories.mercedes-benz.com

 

[LGGVW]

The wheel widths - which is highly relevant.

Almost certainly a wrong assumption, I'm afraid. Most Mercedes RWD cars have what's known as a "staggered" wheel setup, with wider tyres and wheels at the rear than at the front.

Okay, I get that. Thank you. However, how do we reconcile the relevance of the width of the wheels (9J at rear vs. 8.5J at the front) with the fact that Mercedes suggests all 4 tyres the same size (245/40/R18) is acceptable for Winter tyres? I mean, if width is irrelevant for Winter tyres, why should it become relevant for All-Season or Summer tyres?

I wonder if a visit to the dealer would help explain this. If I do go to the dealer, I'll share here the answer. ​

 

[LGGVW]

If you take one of each wheel off and look on the inside of the spokes, you will find an MB part number starting something like A211... plus the full description of the rim size, namely:
7.5J or 8J etc - this is the width of the rim in inches and the shape(J) - x18, which is the rim diammeter in inches.
ETxx- this is the rim offset in mm, and is the offset of the hub of the rim from the centre of the rim, important for clearance over calipers when fitting the rim and for the tyres not to rub on the wheel arches.
As said above, a staggered setup is common on MB cars - I have it on both of mine, with 17" rims on both but 7.5J fronts and 8J rears. I can run 245/40 rear and 225/45 fronts, but Blobcat on here has an identical car to my SLK and runs 225/45 all round for winter, but as mentioned you loose rim protection so have to be even more careful not to kerb the rims.

I understand now better the issue. I was not actually aware of this difference in width of the actual alloys.

This may be because I've only started to get Mercedes-Benz cars in 2020 and my first was a C-Class CDi Estate and the tyre sizes were the same, front and back axles. I fell hopelessly in love with Mercedes cars since and recently bought my E250 CDi, and a difference in alloy widths never crossed my mind.

However, as I mentioned in an earlier reply to another forum member, it is not clear why the alloy width is irrelevant in Winter tyres, but All-Season and Summer tyres need to be 265, rather than 245. ​

 

[colinallcars]

I do trust Mercedes Engineering, but if they approve the same tyre size for Winter tyres/both axles, ie. 245/40/R18, then it should follow that the actual alloy wheel size is either the same or the difference is too small to matter that much?

They will specify the narrower wheels all round with winter tyres. I think you get the picture now, you have a staggered setup with wider wheels and tyres on the back. Probably best not to mess with it.