Rim size: different front and back on 'elegance'

[Skiday]

Hi folks

I have I puzzler concerning the standard rims on my C-240 est auto 'Elegance' 2003. I need to fit winter tyres (& rims) for my up-coming ski trip and I have found to my surprise that on the 'elegance' the rear wheels are different to the front. The tyres are the same - at 225/50_R16_92V but , apparently, the front rims are 7J_X_16_H2_ET37, but the rear rims are 8J_X_16_H2_ET32. But I have no way to check this (unless there's something stamped on the rim - where should I look?).

Apparently the ET number is the offset and I have read on another thread that it can be +/- 4mm, but what do the ET numbers quoted mean? Are they mm or just a code. Surely if a c-240 'Classic' can run on same rims all round then it must be possible for the 'Elegance' to do so too. The parts chap at MB said it was to do with traction, but if the rubber is the same then I don't get it.

I can't see anyone on e-bay selling anything other than 4 identical rims, and that's my problem.

Is there enlightenment out there:?

 

[Skiday]

This is interesting, I've just been out to measure the rims with a tape measure and the rears are indeed 1 inch bigger than the fronts but, I looked at the spare and it is stamped clearly as 7JX16 H2 ET37 (smaller, as fronts). So if I had a flat at the back I would obviously put it on there and there is no warning of special conditions for it's use at the rear (like you get with skinny space savers) so the 7J..ET37 MUST be OK on the back in place of the 8J..ET32 surely?

 

[High-Lo]

Hi,

I previously had some 209 Cygnus 16" CLK alloys fitted to my E Class which were staggered like yours.

The tyre sizes (factory standard) are as follows:

Front Wheels
Wheel size 7 J x 16 ET 37
Tyre size: 205/55 R16

Rear Wheels
Wheel size: 8 J x 16 ET 32
Tyre size: 225/50 R16

Do you know what style your alloys are? (or post a pic)

 

[High-Lo]

These were the ones I had. The wider ones are the far left and far right.

 

[Skiday]

There is a set on e-bay the same style here
http://cgi.ebay.co.uk/Mercedes-Benz...ameZWDVWQQrdZ1QQcmdZViewItem#ebayphotohosting

Pity you HAD them - they would be perfect for me

 

[David Nock]

Hi folks

I have I puzzler concerning the standard rims on my C-240 est auto 'Elegance' 2003. I need to fit winter tyres (& rims) for my up-coming ski trip and I have found to my surprise that on the 'elegance' the rear wheels are different to the front. The tyres are the same - at 225/50_R16_92V but , apparently, the front rims are 7J_X_16_H2_ET37, but the rear rims are 8J_X_16_H2_ET32. But I have no way to check this (unless there's something stamped on the rim - where should I look?).

Apparently the ET number is the offset and I have read on another thread that it can be +/- 4mm, but what do the ET numbers quoted mean? Are they mm or just a code. Surely if a c-240 'Classic' can run on same rims all round then it must be possible for the 'Elegance' to do so too. The parts chap at MB said it was to do with traction, but if the rubber is the same then I don't get it.

I can't see anyone on e-bay selling anything other than 4 identical rims, and that's my problem.

Is there enlightenment out there:?

As above post, the CLK W209 Avantgarde certainly has different wheels and tyres front to back, but that's well known and documented in the manual.
However I can't see the point of having the same size tyres on your car, on different rims. Has there been some 'business of the monkeys' as Poirot would say? What is the manufacturer's spec in the handbook?

 

[Rory]

Apparently the ET number is the offset and I have read on another thread that it can be +/- 4mm, but what do the ET numbers quoted mean? Are they mm or just a code.

Stuff on ET here: (the number is stamped on the back of the rim, and it's measured in mm):
http://www.driverstechnology.co.uk/wheel-offset.htm

Different size front and rear wheels is known as "staggered" and any Avantgarde models have this, but I'm not aware of Elegance models being fitted with staggered setups (at least not from the factory).

My car has 7J fronts and 8J rears and as other have pointed out, I think you have the "wrong" size tyres. I don't knwo how critical it is (ie whether 225's are OK on 7J wheels) but my car has 205/55R16 front and 225/50R16 rear. The different aspect ratios are necessary to keep the tyre circumference near as dammit the same otherwise you'll get speedo errors and ESP realted issues (such as cruise won't work).

 

[alec2]

tyre size

I have attatched a copy of the 2002 wheel info for the c-class.

Well I have tried to.

Alec

 

[bigasotonuk]

Hi,
Different wheel widths quite common on Mercedes my AMG C43 has 7.5J Front, and 8.5J on the back, with a 7.5J as a spare.
I have 225's on my 7.5J front wheels, this size was standard from the factory.

 

[Skiday]

Alec2 - I was about to do the same to show that the owner’s manual is far from clear. It gave two wheel sizes and three tyre sizes but it says nothing of why the various sizes should be used or in what combination. I think the book requires much more clarity. Perhaps I do have different tyres from original, but the books seems to show that 225/50 tyres can be fitted to a 7J OR 8J rim.

I have now concluded (& MB parts guy agrees) that to fit winter tyres my rims must be 7J all round and that is what I'm going to get. I can see that an 8J at the front would likely foul the suspension, and the book seems to be saying that the 8J rim is only for a 225/50 summer tyre.

Indecently. I popped into my local "National Tyres And Autocare" in Newport IoW for a quote on winter tyres and the chap quoted £105 each for Avon and £167 for Pirelli. I looked online (after falling over faint and getting back up again!) and came across "Tyre Shopper" and for exact same tyres and sizes they quoted £82 and £127 fully fitted. When I used there fitting service finder from my postcode, guess who my nearest agent was - that's right - "National Tyres" Newport IoW!!!!!!!

 

[Rory]

Alec2 - I was about to do the same to show that the owner’s manual is far from clear. It gave two wheel sizes and three tyre sizes but it says nothing of why the various sizes should be used or in what combination. I think the book requires much more clarity. Perhaps I do have different tyres from original, but the books seems to show that 225/50 tyres can be fitted to a 7J OR 8J rim.

Looks like your setup is perfectly OK (for summer tyres). I am surprised (based on my setup) that 225's will go on 7J's, but from looking at online guides they seem to suggest that's absolutely fine. If anything I would say my 205's seem to bulge over the 7J's.
In fact most of the guides say 7.5J is the max for 225's, yet mine are on 8J's and look fine - they don't look stretched wide onto the rims.

 

[High-Lo]

There is a set on e-bay the same style here
http://cgi.ebay.co.uk/Mercedes-Benz...ameZWDVWQQrdZ1QQcmdZViewItem#ebayphotohosting

Pity you HAD them - they would be perfect for me

Hi mate - These are 16" Electra alloys

Linky

Technical Information

B6 number: B6 6 47 2120
Wheel size 7 J x 16 ET 37
Tyre size 205/55 R16*

B6 number: B6 6 47 2121
Wheel size 8 J x 16 ET 32
Tyre size RA 225/50 R16

The tyre sizes from the factory would have been as above

 

[High-Lo]

Pity you HAD them - they would be perfect for me

I sold those ones and replaced them with 17" Cygnus instead

These are staggered as well with tyre sizes 225/45R17 fronts and 245/40R17 rears on 7.5Jx17 and 8.5Jx17 rims.