I'd like to know what you all think is the optimal wheel and tire size for the lowest lap times in a W203 Sport Sedan with 189 hp at 2185 lbs. I'm thinking it would a 17x8 with 225/45 all around, but maybe it's a 16" combo that's best...

Let me know what you experiences tell you. I don't need any lessons on theory, thanks.

Along the same lines for low lap times, what do you all recommend as necessary track preparation for a 2003 W203 K (M271) SS. Car has 60K miles and has only had dealer maintenance. I thinking of putting better pads at least, as I have heard that these brakes will fade in a jiffy. I have quite a few track days under my belt so I will be pushing this puppy as hard as I can. Shocks and springs have already been "upgraded" from stock with performance, not aesthetics, in mind, otherwise stock.

Thanks. Here's to track junkies!

 

remove the spare tire, rear and passenger seat, radio, and any other unnecessary weight you can find...

for pads, go with porterfields

 

Thanks for suggesting to go all out, but I don't think I'll do more than remove the spare, it that doesn't upset balance. I'm not trying to break a record for a C at the tracks I visit, but I'd just like the car to be mechanically at it's best on street worthy gear. No R compounds.

Poterfields? Which model, if applicable and what are they like? I usually go the Hawk Blacks for double duty, but for this car, I'm leaning toward something less agressive to better match it's personality for the streets. Anyone happy with Hawk HP Plus, Mintex, or Ferodo DS? With a pad upgrade, will I still see serious fad issues in 20-30 minute sessions? That would be a real damper so I'd like to make sure that doesn't happen, even the first time out.

Thinking more about the tires I really think I can do best with 235/40 tires on 17x8s, however I do realize that this would put it 15 mm smaller in diameter resulting in a few minor draw backs such as a spare that doesn't match, taller fender gaps and a rougher ride. Anyone prefer 235/40 to 225/45 on 8s?

 

Toyo makes a 245/35/17 tire that would be a good choice if you have 17x8.5" rims all around.

Jeff

 

Other than what has already been mentioned, there are a few things that you should think about also.

What Track, Track Conditions, Wheel Alignment, Tires/Tire Pressures, What suspension tuning you have now, What your cars gearing is so you optomize your gear ratios for best acceleration with out hitting the rev limiter when entering a braking zone (Tire size effects this also)

Preferably, you would want the smallest diameter wheel (which would be the lightest) that clears the brakes, and the widest wheel possible to optimize tire size. Stuff the widest tire you can fit. Then you'll barely have to brake for corners and can maximize cornering speeds. In a low Hp car, it becomes a matter of conservation of momentum, since what ever speed you lose takes too much time to regain back.

If you are using the stock sport 17x8 inch 7 spoke wheels, you can fit 245/40 R17's on them, which work really good on that size wheel.

For brake pads, I like Performance Friction 90 or 93 compound.

One thing I want to know is, how you have the weight of your car at 2185 Lbs

 

Thanks for your input!

I agree that it's all about holding your speed through the turns in low hp cars. I got this weight from a generic car info sight, like Edmunds, but I can't remember. I'll confirm that with the sales brochure, but it seems to the the lightest C Sedan that was imported to the US...

The stock wheels are only 7.5" wide, so 245 would be pushing it. I guess I should look for 8.5" rims and use 245 tires all around, but will these easily fit the front with say a ET35 wheel? with or without the bigger 4 piston calipers? I'm looking to get these if I need them to keep from fading, but otherwise I don't want the extra weight.

What's the difference between Performance Friction 90 and 93? Are they strictly track compounds, like the Hawk Blue, or are they dual purpose like the Hawk HP Plus? Will I have fading issues with the stock "small" brakes. I frequent SF Bay Area tracks such as Infineon, Laguna, and Thunderhill, Farley and Willow Springs are a bit too far.

I'm not going to try to get the lowest times, so I wont be changing differential or gearing. I'm just looking to have the most fun with a "street" prepped car, and most of the time this will be a street car, so I'm not sure I'll be able to take full advantage of the 245 if I take into account the decreased gas mileage and weight gain.

 

I thought the those 17 inch 7 spoke wheels were 8's, maybe I'm wrong, I'll have to go check. Either way, I'm running 245/40's on those wheels without a problem. The wider wheels should fit correctly with the correct offset, You can check that here: http://www.1010tires.com/WheelOffsetCalculator.asp
Sometimes increasing the unsprung weight is something you can't always get away from if the performance increase is greater than the performance decrease.

The Performance Friction brake pads 90/93 are Track Pads. I used the 90's on the street and had no issues with them at all, they have good initial bite and good feedback. The higher the number the more of a track pad they are and more abusive they are to brake rotors. Hawk Pads are good, the HP+'s are more of a street performance pad, they may survive a track day or 2 depending on how much braking is needed, but for serious track driving I recommend race pads. You could always change them at the track, its not a big deal to change.

Infineon/Leguna Seca are both fast tracks. You need good high speed stability in corners and very good brakes to keep them from fading.

What's the wheel alignment set as on your car, that will also make a huge difference as far as high speed cornering/high G loading.

 

Hey, awesome. Thanks for confirming that I can stuff 245's in the front even with the 7.5" ET37 wheels, if that is what you have. There is an optional 8.5" size for those wheel available through the MB parts department, but US cars only ever came with were 7.5" all the way around. I wonder if the 8.5" rear ET34 wheels will fit in the front. Those would be perfect for 245s. Do you know how much those C7 7 spoke wheels you are using weigh?

So you say I'll need good brakes at the faster tracks... Pads, themselves, may or may not make it? I'll see how far they get me the first time out, but it sounds like I'll have some fun with street/track pads before for I cook them.

BTW, I checked the MB published curb weight for a 2003 C230 SS and it's confirmed to be 3185 lbs. Which W203 do you have and what what do you do with it at the track? Just kick it around, like I plan to do? What brakes do you have? I have the stock alignment right now, but I'm thinking of getting the adjustalbe bolts to get more front camber. But, I'll see how it goes first.

BTW, is it best to switch it to the "dyno" mode for track duty? I haven't tried this, but I read it in another post. Not sure if it works for 2003+ cars, though; some have not been able to do it. Please let me know how you are getting around that electronic leash.

 

Yes, you can stuff 245's on 7.5's but they would be better on at least 8's or wider. I have 245's on 8's. I've stuffed 225/45 R15's on 6 inch wide wheels and did not have any issues, that was on my friends VW.

You can fit 245/40's in the front. The tire is wider, but overall diameter is smaller than a 225/45, so you will not run into any strut clearance issues. It will come close, but not enough to hit the strut.

I don't know how much the wheels weigh, I haven't checked that yet.

I do not have a W203, I own W202. I have a set of W203 Sport Wheels for my W202 with 245/40's on them

As far as brakes, I have stock sized cross drilled rotors, and was using Porterfield R4's. I burned through those and lost the brakes after about 8 laps at Watkins Glen last year. Luckily I had a spare set of stock pads to put in so I could get home. I'm planning to upgrade to something else, but not sure what yet.

Only recently have I started using the car for Autocrosses and Track Events. I had set the car up years ago for it, but had been using my BMW race car for most events until the engine blew on that last year.

I recommend getting the alignment checked and installing the bolts. The W203 does not come with much front negative camber from the factory. You will overheat and burn up the outer edge of the front tires. That will also cause lots of understeer.

Usually just turning off the ESP is enough for track driving. Unless you are a really good driver and know how to react if you make a mistake, I would not use the "Dyno Mode". There is no sense in turning off a safety feature just to squeeze a couple tenths of a second off you lap time. You will have enough of a problem putting the power down with an open differential anyway. Also you will see that wether you have the ESP on or off, your lap times will be very similiar as it is.

 

Thanks again Mercedes Tuner.

I stand corrected on the 7 spoke wheels. The 8.5" did come on the rear of coupes in USA, at least in 2005.

I'll see how it goes with just the ESP off, but from what I can tell in the wet, it seems like it may be a problem on track.

 

If you are doing the event in the Rain, then I highly recommend leaving the ESP On.