Off (he) sets (again)

[portzy]

Another one for our wheel experts. If I have a new rear wheel that, say, has an offset of ET 34 and I fit on to the rear of a car which calls for (standard OEM fit) ET 30 will the wheel and tyre combination be 4mm further out from the centre line of the car or further in. Similarly if I fit a new rear wheel which has ET 36 what will be the consequence in respect to ET 30?.

If, no matter what else, the brake component clearence and wheel arch clearence is adequate and safe in respect to the OEM set up does it really matter what minor ET difference there is?. Is ET measured in mm, i.e. ET 36 being one mm difference in offset than ET 35?

Portzy.

 

[andy_k]

I'll try and answer ...

would the wheel and tyre combination be further out?. this would depend on whether or not the rims were the same width, assuming they were identical, then yes the whole thing would move out 4mm

if you fit an et36 wheel of the same width then you are increasing your vehicles track by 12mm which will shift the stress on cucpension components and may be enough to have an adverse affect on handling - I'd be loath to try that one

Yes ET is measured in mm and the brake clearance is often very tight so a difference of a couple of mm can make all the difference under load.

see if this helps

Of course I could be completely wrong

Andy

 

[R2D2]

Andy is right. there are threads on here from those who have had brake clearance problems. 6mm is a lot in suspension geometry terms. You know when you see a car and it has nice wheels but the car looks "wrong" its because it has the wrong ET and or width of wheels.

My original wheels were ET37 then I fitted ET35 alloys that everyone thought were OK, but when I fitted ET37 OEM wheels everyone said "perfect".

Basically dont screw up your cars looks or handling by fitting the wrong wheels. Get the right wheels in the correct Offset.

 

[portzy]

Cheers mates.

Thats exactly what I needed to know. I thought it would or could have been a fool around too far (unsafe) I'll tell my mate who is selling his wheels that its a case of thanks but no thanks.

Portzy.

 

[andy_k]

all of this of course depends on the size of the rims as well, as th rim width increases the offset decreases and the same is true in reverse, so if you were fitting slightly narrower rims then the offsets you mentioned would be about right

Andy

 

[Will]

Just to throw another thought around, what about standard fitment staggered wheels, and factory approved OEM optional wheels?

Eg, Mercedes specify in their actual official wheel catelogue that a W202 can use a number of different wheels, with different diameters, widths and offsets.

Just as an example AMG style I 7.5J x 17 ET37 - where as the AMG style II rims are also 7.5J x 17 with an offset of ET35. Same width and diameter, different offset.

If you go for 17 x 8.5J rears on the style II, the offset should be ET30. These are Mercedes-Benz published fitments.

I think there are tolerences, and it pays to be careful when carrying out any changes or modifications to your car - but I doubt that it is such a precise science that 2mm would become such a serious issue otherwise Mercedes-Benz would not recommend that as a fitment.

Will

 

[portzy]

Actual situation.

OK. A specific style of wheel, namely the one you see below on my coupe.

That style, (Alshains) in 7.5J and 8.5J, carries the same two part numbers, (and therfore the same characteristics), right across the range of fitments for all the range of cars except the A class. So, clearly, there can only be two wheel characteristics to consider.

The offset of the above (rear) 8.5J model is ET34. If I fit them to a car which has wheels which are presently 8.5J with an ET30 I assume that places the new wheel +4mm further away from the centre line of the car?. Similar treatment at the other side would give a combined track difference of +8mm?. Assuming the brake/suspension clearences were o.k. Would that kill the looks and handling?. Is +8mm THAT big a deal, really?. Im no expert you see.

The offset of the above (front) 7.5J model is ET37. If I fit them to a car which has wheels which are presently 7.5J ET36 I assume that places the new wheels +1mm further away from the centre line of the car. Similar treatment at the other side would give a combined track difference of +2mm. Assuming clearences etc etc, would that kill the looks and handling similarly?, 2mm?

Portzy.

 

[Will]

OK. A specific style of wheel, namely the one you see below on my coupe.

That style, (Alshains) in 7.5J and 8.5J, carries the same two part numbers, (and therfore the same characteristics), right across the range of fitments for all the range of cars except the A class. So, clearly, there can only be two wheel characteristics to consider.

The offset of the above (rear) 8.5J model is ET34. If I fit them to a car which has wheels which are presently 8.5J with an ET30 I assume that places the new wheel +4mm further away from the centre line of the car?. Similar treatment at the other side would give a combined track difference of +8mm?. Assuming the brake/suspension clearences were o.k. Would that kill the looks and handling?. Is +8mm THAT big a deal, really?. Im no expert you see.

The offset of the above (front) 7.5J model is ET37. If I fit them to a car which has wheels which are presently 7.5J ET36 I assume that places the new wheels +1mm further away from the centre line of the car. Similar treatment at the other side would give a combined track difference of +2mm. Assuming clearences etc etc, would that kill the looks and handling similarly?, 2mm?

Portzy.

Hi Portzy,

I would personally feel that the 1mm on the front is virtually unmeasurable! Certainly wouldn't concern me anyway.

With regards to the rear wheels, 4mm I would also say is highly unlikely to give you much (if any) grief. Should be further spaced away than the existing wheels - so if the design is similar on both wheels you won't be worrying about brake caliper clearance etc (very unusual from what I've heard). As long as you have at least 4mm space in your rear wheel arches then it should be a simple fit without any grief.

Leaving perhaps just the 8mm wider track to consider. Depending on your driving style I would think it unlikely that you would notice any serious changes in your car's handling characterstics. Maybe the 4mm might leave the tyres to wear ever so slightly differently, but again, I don't see any major concerns here.

Obviously all IMHO do you may want some other opinions before you commit to choosing anything!

Good luck

Will

 

[Chris Murray]

The Alshains will fit all C/CLK/SLK and W210 models without problems.
As Will said, there is quite a large range of acceptable offset values approved by Mercedes for any given model, and at times it seems quite arbitrary!
8.5 rears can either be ET34 or ET30, both work fine! Also, there is far more room under the wheelarches than you think, especially at the back where the wheels are not required to 'steer'..
Full specs of Alshain are here:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=72254&item=7968846292&rd=1
There are different part numbers front and rear.. sorry for picking up this thread so late

 

[portzy]

Will, Murray.

Thanks for that. When my coupe goes I have to remove the rears, which are 245, and put back on the 225s. That would leave me with a spare pair which, if I could not use them on another potential car purchase, would be usesless. Not now though

Thanks again.

Portzy.