Can I put wider than 205's on a C280

[Stulc]

On a standard 16" rim (only thing is I dont know the width of it..), it's 205/55/16 as standard, what I dont understand is take the BMW 525 it has 225's as standard and the 99' C280 V6 is the same weight if not heavier and just as much power so why not that size (as standard) fitted.

 

[yvrbenz]

Yes, you can.

The short answer is in the Title line of my post. To elaborate a little:

BMW and Mercedes-Benz, although they have always been head-to-head competitors, have different philosophies:

BMW has always been a driver's car first and a luxury car second.

Mercedes-Benz, on the other hand, has been a luxury car first and only recently injected a sporting image back into the brand.

The contrasting philosophies are most evident when looking at the North American m\product lines. As a result, BMWs tend to be equipped and setup with more sport/performance driving components or specification while MBs tend to focus more on things such as comfort, ride quality, fuel economy, etc.

Realize that while MB's focus and BMW's are not necessarily mutually exclusive, they are in different directions and require compromises.

To bring it back to your question of tire choice:
Wider tires offer a greater contact patch and therefore more grip. They also enhance cornering stability and handling.

However, a greater contact patch means more friction (aka rolling resistance) which has an impact on fuel economy. Wider tires also cause a car to be somewhat more inclined to follow the ruts worn into the asphalt by years of being driven on.

Also, in order to keep the rolling circumference as close as possible to the factory spec, a lower aspect ratio tire is required PARTICULARLY if you Plus-size (change the diameter of) your rims.

ie. 205/55-15 vs 225/45-16

This means that the tire's sidewall will be a little stiffer taking away from the ride quality.

In general, changes made to improve the performance of a car will have to be compensated for by a reduction in fuel economy, ride quality/comfort.

 

[yvrbenz]

If you DO decide to go for bigger tires.

You will need to figure out which size is most appropriate. I recommend that you do some research on tire and rim tech so you have a complete understanding of what implications the changes will have.

For example, if the size you choose results in your wheel's diameter being significantly larger than OEM (also referred to as being "taller") you will find that your car will have a higher top speed while acceleration will suffer. Also, your speedometer will register a speed that is less tha your actual speed.

There are other side-effects as well, I suggest going to www.tirerack.com which has several informative tech articles.

 

[Stulc]

Thanks for the reply, it's quite indepth with your explaining and I understand what you mean, I know what you mean also when you say about a "taller" wheel/tyre ans the speedometer calibration, I had that a few years ago with a car.

It was also my first experience of following the ruts in the road too with my first BMW a few years with the 225 tyre's, it was quite unerving when it happened, I'll check out the web site you sent too, again thanks.

 

[tom7035]

Good information above, but also be aware if you ever consider changing to wider rims, the ET, or 'offset', number (e.g. ET32, ET41 etc.) is extremely important to ensure they come within your car's spec. or you could have all sorts of problems with fouling of arches, suspension components etc. It's surprising how many have never heard of this measurement. It is usually stamped on the inner face of the wheel.
There's some good information regarding this on the forum if you search, and here is just one example;
http://forums.mercedesclub.org.uk/showthread.php?t=12885&highlight=offset
Cheers, Tom.

 

[clive williams]

On a standard 16" rim (only thing is I dont know the width of it..), it's 205/55/16 as standard, what I dont understand is take the BMW 525 it has 225's as standard and the 99' C280 V6 is the same weight if not heavier and just as much power so why not that size (as standard) fitted.

To add my sixpennysworth. To prevent a mass of associated problems it is best to maintain the same overall diameter of the tyre when changing the wheel diameter/width. Calculate the overall diameter using the tyre designation say 205x55x16 = 205mm x 55% (=o/a height of tyre wall) x 2 (top and bottom) + 16 x 25.4 (to convert wheel rim dia to mm). Therefore, the overall dia for this wheel/tyre is 632mm. Similarly, for a 225 x 45 x 17 is 225x.45%x2+17x25.4 = 634mm. The difference in the o/a diameters is 0.3%, which is well within the tolerence allowed for speedometer accuracy of +/- 5% (BS) or (+10% - 0%) (Euro Std).

For the appropriate wheel width check out Yokohama Tyres Web site as their tyre choice charts give range of acceptable wheel widths and the most appropriate size.

Of more difficulty is the ET amount. This is the offset to the outside (+ve)from the centreline of the wheel rim of the inner mounting face to the wheel i.e. the face that fits to the hub. So for example, a standard wheel of 7J (wheel width in inches) x 16 (wheel dia in inches) ET41 means that the back face of the wheel flange (face of hub) is 7x25.4/2 (centreline of wheel in mm)+ 41 = 130mm from the inside edge of the wheel. This 130mm should be maintained as any increase in this figure would result in potentially the tyre/wheel rubbing on the inside on suspension or body - check the standard condition for clearance at all positions of the wheel. New c/l position for o/a width say 8J (203mm) = 102mm subtract this from 130mm to give a new offset of ET28.

Therefore, the new wheel/tyre combination could be 225x45x17 on an 8Jx17 ET28 rim. But, will the extra 25mm of rim width on the outside of the wheel foul the body - only trial and error will determine this. Also the extra offset will impose greater wheel bearing loads, which must be considered.

I have my own views on tyre width and aspect ratio that have been discussed elswhere in the forum but don't naturally assume that the car will have better roadholding or handle better on wide/low profile tyres.

Clive

500E
E320CDIT210