new wheels

[stevie boy 01]

i am going to change my alloys .. any of you got any idea what to put on .. its a 2000 modle 202 sport (c200)the off set is 37 so what would suit .. i dont want the car to tram line as i have been down that road before .. is 17inch ok its got 16 at the mo.. help..

 

[television]

i am going to change my alloys .. any of you got any idea what to put on .. its a 2000 modle 202 sport (c200)the off set is 37 so what would suit .. i dont want the car to tram line as i have been down that road before .. is 17inch ok its got 16 at the mo.. help..

!7" are a fine middle of the road wheel you can deviate al little on the ET larger wheels come down a touch. If you are too far out your ESP will malfunction. Keep to MB wheels.

Malcolm

 

[stevie boy 01]

thanks malcolm.. for the info .. so et35 is ok then ...

 

[television]

thanks malcolm.. for the info .. so et35 is ok then ...

Yes that is fine,its the same thing on my car,there is about 4 (down)difference for my larger wheels.

Good luck with them,makes the car look much better,though the ride will be a touch firmer,the handling is much better.

Regards Malcolm

 

[Bolide]

Bear in mind that ET normally changes with wheel width. So if you have 7" wide wheels now (for example) and go to 8" then the ET should change by about 12 mm

I could explain it but it's difficult to put into words

Nick Froome
www.w124.co.uk

 

[television]

Bear in mind that ET normally changes with wheel width. So if you have 7" wide wheels now (for example) and go to 8" then the ET should change by about 12 mm

I could explain it but it's difficult to put into words

Nick Froome
www.w124.co.uk

Sorry Nick that is not correct to change by that much.

My standard factory 17" 8½J wheels have an ET of 35 and my and my factory 18" 9½J wheels have an ET of 33.

My 129 only changed by 4

I do not know of any thet change more than that.

Malcolm

 

[stevie boy 01]

thanks again malcolm .. some man .. going to get 17inch but something diffrent........

 

[Bolide]

Sorry Nick that is not correct to change by that much.

My standard factory 17" 8½J wheels have an ET of 35 and my and my factory 18" 9½J wheels have an ET of 33.

My 129 only changed by 4

I do not know of any thet change more than that.

Malcolm

Of course you're right, but I was illustrating a point, which is why I said "normally"

If the wheel width alters by 1 inch then the ET should change by 12 mm (ie half the change of width) to keep the centre of the tyre contact patch in the same place. If MB choose not to do that then I'm sure they're working within the tolerances they've calculated & measured

The other factors to be taken into consideration include the clearance between the suspension leg & the tyre edge, clearance within the arch and whether the wheel & tyre protrudes beyond the arch and any of these may cause a change to be made to the ET

So to be more accurate I should say the offset should theoretically change with variations in wheel width by half the change in wheel width but the observed change in recommended wheel fitments may not fit the theoretical model

I was trying to be brief!

Nick Froome
www.w124.co.uk

 

[television]

Of course you're right, but I was illustrating a point, which is why I said "normally"

If the wheel width alters by 1 inch then the ET should change by 12 mm (ie half the change of width) to keep the centre of the tyre contact patch in the same place. If MB choose not to do that then I'm sure they're working within the tolerances they've calculated & measured

The other factors to be taken into consideration include the clearance between the suspension leg & the tyre edge, clearance within the arch and whether the wheel & tyre protrudes beyond the arch and any of these may cause a change to be made to the ET

So to be more accurate I should say the offset should theoretically change with variations in wheel width by half the change in wheel width but the observed change in recommended wheel fitments may not fit the theoretical model

I was trying to be brief!

Nick Froome
www.w124.co.uk

Nick, I am not trying to be right,I do not understand the reasoning and the working it out either, when I first got into this ET thing was with my 124.

I feel sure that years ago it was safe to work on your calculations, That was also my way of thinking and I did that before ESP came along,exactly as you say,somehow the differences are getting smaller,I had much bigger difference on the 129 than on the 230.

If it is also to do with the wheel clearing other components,and this must come into it, then this sends a lot of info that we are given out of the window.

I respect you very highly and the knowledge that you share here, this is just a strange subject.

Best regards. Malcolm

 

[whitenemesis]

Probally best stick with MB recommendations. I can't fit a finger between tyre and spring cup on my set-up!

 

[television]

Probally best stick with MB recommendations. I can't fit a finger between tyre and spring cup on my set-up!

I agree with you completely, and would only go so far as to say where there was an option from new and that was 1" larger diameter thats OK.

Some of the BMW boy racers over do it to the point that the wheels look silly.

Malcolm

 

[television]

Of course you're right, but I was illustrating a point, which is why I said "normally"

If the wheel width alters by 1 inch then the ET should change by 12 mm (ie half the change of width) to keep the centre of the tyre contact patch in the same place. If MB choose not to do that then I'm sure they're working within the tolerances they've calculated & measured

The other factors to be taken into consideration include the clearance between the suspension leg & the tyre edge, clearance within the arch and whether the wheel & tyre protrudes beyond the arch and any of these may cause a change to be made to the ET

So to be more accurate I should say the offset should theoretically change with variations in wheel width by half the change in wheel width but the observed change in recommended wheel fitments may not fit the theoretical model

I was trying to be brief!

Nick Froome
www.w124.co.uk

I think that I owe Nick a bit of an apology when talking about this.

It is very easy to forget that not all cars have ESP in fact no 124 does have it. though my posting here was technically correct for this car I may have given out the incorrect info in the past. Anything that I have posted in the past would have been correct from the safety angle and within the spec laid down by MB

No one has ever picked me up on this point and I have posted many times on this subject and If you do not have ESP then a much wider deviation is possible.



Malcolm

 

[Bolide]

Suspension is designed to have the centre of the contact patch in the "right" place for the various geometries to work correctly. If you move the centre of the contact patch by changing the rim width and/or ET you may move outside that "right" zone, but the size of the zone and the tolerance of the zone will determined by lots of factors and will be known only by the manufacturer

If Mercedes vary the ET with different wheels a few mm inside this theoretical zone then they'll be working within the limits they know

With respect to tyre - suspension leg clearance, this is probably the limiting factor with large increases in rim width. When putting 8" rims on my BMW 2002, which probably had 5s originally, I'm limited in how far I can push the rim inwards by leg - tyre clearance. In theory the wheel should be inset by an additional 1.5" (half the increase in width) to maintain the centre of the contact patch in the same place but I'm sure that's not possible. As the tyre is relatively tall (60 profile), there will be plenty of tyre distortion under race conditions and I'll need to leave decent clearance. With a modern Mercedes with 17" or 18" tyres, wide rims and 40-odd profile tyres I'd think you'd be hard pressed to get the tyre to deflect much at all under road driving conditions. So I'd expect the problem to be less

I think you'll always be safe using manufacturer-suggested wheel sizes and offsets, so log as you observe their caveats. I do wonder about much bigger wheels on older cars with softer suspension - I would expect 18s on a W124 to create all kinds of problems for lots of reasons, not least the fact that the suspension won't keep the tyre perpendicular to the road

I'm going to update my tyre size calculator page with an offset calculator and a diagram to try and explain it better. Till then you can use it to work out equivalent tyre rolling diameters with different rim diameters and tyre profiles:
http://www.bolide.co.uk/actions/info.taf?page=tyresizecalculator

Nick Froome
www.w124.co.uk