[W126 Coupe] Increased Wheel (Rim) Diameters

[Josh Allen]

Flodur2 at aol.com wrote:

> Will someone enlighten me as to whether there is any real desirability 

> to fitting wheel (rims and tires) of a diameter greater than the 

> standard size fitted to a car, and specifically MBs, other than just 

> for "looks". Although I am not directly involved in vehicle design, I 

> am a professional mechanical engineer and well acquainted with 

> consideration of dynamics, vibrations and structures. Other than 

> appearance, I see very little to suggest that an increased tire size 

> is an attractive proposition. Without going into details, it is 

> desirable to minimize the (unsprung) mass or weight of a tire and rim. 

> But the combination has a certain stiffness which was allowed for by 

> the designer of the car or suspension to yield a good tradeoff in 

> comfort, handling and reliability. Changing these characteristics 

> changes the design point, not necessarily for the better, in my 

> opinion. So what's the attraction of plus sizes with the associated 

> smaller sidewall heights (degraded ride comfort) and other induced 

> problems such as rubbing on the chassis?

>  

> Rudolf Boentgen, PE

> '96 S600 Coupe

> '98 S320 Sedan

> '02 SL500 Roadster 

If you are after a stiffer ride, or more sporty suspension response than 
the vehicle was originally designed to target, the shorter/stiffer 
sidewall makes an easy way to change that.

In my car's case, I am not the affluent middle aged business man who 
wants to flaunt his fine taste in automobiles.  Instead, I enjoy the 
power of the car, but also enjoy a reasonably taut suspension response, 
which is a little difficult to get in a car of this size, especially 
when it was engineered to be refined in all it does. (Other than the 
nice shove in the rear when the pedal meets the floor...)

That being said, in a few years I may change my opinion on this and 
change to a smaller diameter wheel and tire combination, putting my ride 
back to a cushy feeling touring suspension setup.  Who knows what may 
happen, but it's a matter of 20 lug nuts and it's done.

-Josh
'84 500SEC euro