jetflyboy

Hello People,

My 09 C300 has 18" low profile staggered Contisports 3 (OEM) tires mounted on AMG wheels. I keep the pressure lower than what is on the fuel cap. I use 31-35 to make the ride less harsh.

I have 35,000 miles on these tires and was wondering if I should go with hight profile tires, or is that not going to help and will look bad? My profiles are 40 and 35.

Anther thing, what tires are you using on your car?

Thanks a bunch

mr inkredibul

Higher profile will throw off your speedo, braking and handling. What are you trying to help with? Ride comfort? Go down to 17 inch rims. That will hep the most.

AlonzoMosely

To answer your second question, I am rolling with Continental DWS on 17" rims and I could not be more pleased with the combination of ride comfort and cornering and wet weather handling. I take the entrance and exit ramps with a 25mph speed warning at 50 give or take with no skidding and the car is smooth and comfortable on highway straightaways. In wet weather I am not hydroplaning at all, whereas I was hydroplaning all over the place on the stock tires that I had before I got the DWS's. I am a nitpicking perfectionist who has a complaint about almost everything but I love the DWS on 17" rims and cannot find anything to complain about with them.

Sportstick

The primary reason for purchase for 18" wheels is appearance, if you are visually sensitive to and impressed by that 1" change in diameter. From most dynamic aspects, larger diameter wheels are directionally incorrect due to higher mass. Although some of the losses in acceleration, braking, and fuel economy are relatively minor, ride deterioration can certainly be felt. You can get extremely good performance with improved ride comfort from 17" wheels/tires. If you buy some good quality 17" replica wheels (make sure you get a proper offset), and some DWS, Michelin Pilot Sport A/S Plus, or Bridgestone Pole Position RE970AS, you will have excellent handling and improved comfort in a variety of weather conditions (although I always suggest dedicated winter tires for snow conditions). Once you buy your new set-up, you should have little trouble selling the 18" wheels here, as many members feel the appearance of larger wheels is important to them.

rb23lb

What about getting 18" DWS tires on his car?

You recommended to me that 18" DWS would be a great alternative to the stock 18" tires for more ride comfort.... Why do you recommend changing out the entire wheel size here now?

I am getting tires in the next month or two and want to know why you recommend decreasing wheel size here but in the other thread just changing tire type....

thanks
rb

jetflyboy

Thanks for all the replies. I really like the looks of the AMG rims, but when it comes to low profile tires, the looks are of little importance to me. It;s just that the car came that way. Performance and comfort is what I'm looking for. Going from 38 psi on the rears to 35 psi has made a noticeable difference in improving the ride.

mr inkredibul said that changing to a higher profile tire will affect the speedo and brakes and that is not a good thing. And from everybody else, I am concluding that if I am to keep my 18" MG rims, I have to continue using 225/40-18 for the front and 255/35-18 for the rear, adjust the pressure a bit and just get used to it. Or perhaps buy different brand tires that are better than the OEM contis 3 that I got.

I should also mention that this is my first MB as I came here from a BMW 5 series.

mr inkredibul

Depends on what is important to you. Rim size will be the single most significant thing that you can change to improve ride comfort. If you don't want to have 17" wheels (like me, I think they take away from the overall appearance) you can do other things to improve ride comfort as you define it to be.

Sportstick

No problem and a fair question. I was likely reacting to my perception of your question versus the discussion here which already entertained moving down in wheel size to increase ride comfort. If you are staying within 18", DWS were, are, and will be a way to improve ride comfort over ContiProContact, or similar other tires. However, in all cases, moving down to 17" will make another noticeable step of improvement. I probably believed you were not entertaining moving down a size, and if I mis-read that, I apologize for not laying out all the alternatives. Sometimes, I get a bit tired of getting chewed on by the larger wheel crowd, but since Mr. Inkredibul brought it up here, I was agreeing that this would certainly help with ride comfort. Hope that clarifies, and if I didn't provide a sufficient answer earlier, my regrets.

RLE

I'm sure that changing to another brand of tires and retaining your lower pressures will go a long way toward eliminating the poor ride.

I would definitely advise against buying 17" aftermarket wheels when there is an easier and cheaper way.

coolvi

I went for quietness over performance with my new summer tires: Been on a set of DWS (225/40/18 F and 255/35/18 R) on 18" C63 rims for two weeks and it's been amazing so far. I run 32 PSI up front and down to 35 from 38 rear after noticing excessive centre wear pattern on the previous PZero's which came with the rims. Much quieter and smoother than the previous tires. Quieter than my Dunlop Wintersport 3D on 17" rims. Ride quality is pretty much unaffected.

sjhugh

I’m surprised you are finding the ride harsh, I must be missing something.

Are there aftermarket alternatives available instead of the stock springs?
If there is and they are softer, to change them out would be a cheap long term alternative.

I thought I’d throw that in for a different approach.

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C300Sport

I agree that Conti's DWS are great tires. My 18" DWSs ride better than my stock 17" Michelins Pilots.

Sportstick

There are some different points of view here, but notwithstanding opinions on where to source wheels if you downsize, here are a couple of points I think are fairly undisputed.

1) If staying with 18" wheels, DWS are about the most comfortable tires you will find while retaining some quite excellent performance.

2) All else being equal (type of tire, wheel, etc.), changing to 17" wheels/tires with its taller sidewall will add the next increment of ride comfort.

How far you wish to go in making changes depends, of course, on how unsatisfied you are with the status quo. Once you buy the 18" DWS, you'll likely want to run them to wear-out, although I think Continental has a buyer's satisfaction provision which allows you to trade for another set of Continental tires in the first 30 days, which might include the same tire in a smaller diameter if the 18" DWS don't offer enough improvement.

lm24

Another vote for the DWS here. I had the same exact experience as you. Going from the stock Contis to the DWS was night and day. No more hydroplaning. I swear these stop better in the rain than the stock tires on dry ground.

kevink2

Unless you mostly ride with 5 adults in the car, and full lugage capacity, there is no need to rear bias the pressure. For light loads, 32 front and rear should be fine.

With same pressures, car sitting on flat pavement, you will notice the front tires are compressed more, reflecting the front weight bias.

For the 08 4MATIC, 17", running 33 front and 32 rear, for mostly solo driving, results in even tire wear (Front still bulges more than rear).

I agree the DWS will help with comfort alot, as the tread blocks are more sparse and softer than usual. Going with the MB 17" AMG wheels with those tires would be extremely comfortable. To check out 17's on a car, drive one at a MB dealer.

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coolvi

I always thought the extra PSI in the rear had to do with the stock tire's wider width and lower profile (than fronts): Must be compensating for load, weight, and all of those extra ratings or something. Can't go into details other than having the vague understanding of the subject.

kevink2

The tire pressure information on the placard is based on formulas outlined in a Federal Motor Vehicle Standard, where the front and rear axle max loads are determined, based on car weight and max passenger + luggage weights, and the tire used.

Even on the C300Lux model, where same tire size is at all 4 corners, the placard pressures are higher in the rear, due to the luggage weight and the 3 adults in the rear seat putting their weight almost directly over the rear axle.

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LandSeaAir

The OEM 18s require low profile tires? I'm confused on what classifies a tire as low-profile because I never thought the option 18s used low profiles.

Also, this makes me wonder if you have the stock 17s and you upgrade to the 18s, do you still follow the PSI recommendations under the gas cap?

If not, then the I guess cars equipped with the optional 18 AMGs have different stickers under the gas cap

rb23lb

great response, thanks for clarifying!

Sportstick

Generally, once the aspect ratio falls below 50, the tire is considered "low profile", which would include the size of the standard 18" tires. If you change from 17" to 18", check out the label on the fuel door of a car which had them as original equipment, and use that as your starting point.

kevink2

... and different pressures listed on the door pillar placard, as well as the 18" tire size(s).

If you change to a different size, +1 or -1, and the new size is not listed on the placard, stickers are allegedly available to cover them with the new info on the sticker.


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