Go Navy

I find the stock tires on my 2012 C350 Sport (225/40R18 front, 245/35R18 rear) to be too hard-riding for my taste.

So, I'm thinking of replacing them with higher profile tires that would provide a more comfortable ride. Not sure what those dimensions might be.

Question 1: Is there room in the wheel wells, esp. front, for higher profiles, while staying with the existing 18 inch rims?

Question 2: can I use the existing wheels? (7.5 x 18 front, 8.5 x 18 rear)

Thanks.....

Sportstick

In order to achieve the results you desire, it will be advisable/necessary to revert to 17" wheels and tires. I did this with our E Class and the results were transformational. I suggest the following:

Find a set of used C Class 17" wheels or look at

http://www.powerwheelspro.com/shop/index.php?cPath=23

for a good value set of 17x7.5 or 17x8 with offsets of at least 44. Get the same size for all four corners, giving up the staggered look (with no measurable performance difference), but saving money. Then, go to tirerack.com and order four 225/45-17 Michelin Pilot Sport AS3 tires and send to a local installer (where you also had the wheels shipped). Drop by for the swap once they are mounted and balanced and sell on the forum the old 18s. There are usually enough folks more interested in the bigger wheel look than comfort to buy them from you. You will be delighted at the improvement in ride comfort.

Go Navy

Sportstick, thanks for that detailed advice. I appreciate it. I was hoping I would not have to buy four wheels, but based on your inputs, apparently I will find it necessary to buy four wheels. Ugh!

Riviera

Yes, you can't use higher profile tires with same wheels you must downgrade to 17" or the speedometer will display a lower speed i don't think it's legal.

You'll sell your 18" wheels in a minute but if you don't need money and think about selling the car in a few years you should keep the 18" and put them back when selling the car and sell 17" apart or with the car, e.g. for winter set.

Pascal

The_colombian

My c350 has 17 inch wheels so I don't have an image of what yours looks like but I've gone from 40 profile to 45 profile on other lowered cars I've had in the past with out issue. I think what you really need it a luxury / soft tire. Going to a 17 inch wheel with a thicker tire will of course do the trick but I don't personally think it's necessary. I would ask a performance shop that specializes in luxury cars about what tire might work best.

Go Navy

Thanks......I think you are right about my needs. Ideally I'd like to keep the MB sport wheels on the car. I'll check with a local source.

Sportstick

If you want to try that approach, be sure to check and compare the tire sizes on the calculator at 1010wheels.com. Note the impact on the odometer/speedometer.

http://www.1010tires.com/Tools/Tire-Size-Calculator

xaran

Sportstick is very correct in his answer.

On my C250 I went from the stock 17" to 18 rims and lower profile tires (same size as you are running in a summer sport tire) and I did notice a little more road noise and a slightly rougher ride. By going to the 18" you do loose about 0.5" of rubber and this in part makes for the change in ride. But tires in general have a lot to do with the noise, comfort and performance and different brands make a big difference.

17" wheels are easy to find as OEM take offs and are available for less than $ 300 but I would suggest that you try going to Discount Tire and talking to them about what your needs are and let them suggest a tire to try. In my area the local Discount Tire Stores will exchange tires if it is a brand, model they suggested and you are not happy with the results. I think you can find a 18" tire that will soften up your ride and give you what you want. Our 35 and 40% side profiles are not extreme at all and there are tires that will ride softly and tires that will perform and grip but may not give you the comfort ride...

edgalang

(free) Step #1...check tire pressure. Make sure you are not over inflated.

(free) Option #1..do an even swap with a local guy. I'm sure there are 17 inch users who want to go 18.

Money Option #2..Stock tire size is...
225/40-18 (front) and
255/35-18 (rear)

Maybe you can replace them with 235/40-18 & 265/35-18

You'll have both wider and taller tires and only be off by 1.3% in front and 1.1% in the rear.

tonyteetime

How about going with a softer (non sport) suspension ?

Sportstick

Technically feasible, but definitely the high cost solution.