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I just had an awesome track day at COTA, but ran into an issue I'm still trying to figure out. After two sessions, or ~20 laps, I was in a corner under high load and all of a sudden my steering wheel was shaking like I was running over bumps. From that moment forward, any hard lateral Gs resulted in this feeling.
Getting out of the car, I asked someone what they thought it could be and they pointed out that my sidewall was worn about halfway down now. For the next session, I bumped up the tire pressure 3 psi, but the issue persisted.
My best guess is that I ran too low a tire pressure and permanently wore down the sidewall. If I would have had a higher tire pressure, this wouldn't have happened. I started the day running 38 psi and ended at 41 psi. (The hot pressure was 5-8 psi more)
Anyone experience this before? Once you roll a sidewall is the tire toast? Or should I have gone up to a cold pressure of 45 psi and the issue would have gone away?
Your tires are probably done. What tires were you using? What width and profile?
I'd start shopping for another set with stronger side walls in the right width and profile for your rims.
The tire is too narrow for track use and once you roll over the tires this much, it's over for that tire. I would run a 245 tire and lower aspect ratio with a more aggressive street/track tire. Your pressures are fine at least from what I see, but would check them with a secondary device. Sport cup 2's and Trofeo R's have stronger side walls. The C63 is not a light weight car. It is stocky and stout. Having said that you do need a strong tire that can take the weight and the abuses of street and track use. You would be surprised how few tires will work on this car. I can could on one hand how many tires will work for this car in street/track conditions
The tire is too narrow for track use and once you roll over the tires this much, it's over for that tire. I would run a 245 tire and lower aspect ratio with a more aggressive street/track tire. Your pressures are fine at least from what I see, but would check them with a secondary device. Sport cup 2's and Trofeo R's have stronger side walls. The C63 is not a light weight car. It is stocky and stout. Having said that you do need a strong tire that can take the weight and the abuses of street and track use. You would be surprised how few tires will work on this car. I can could on one hand how many tires will work for this car in street/track conditions
Mazspeed-it looks like OP is on the factory wheels, and for the sake of this picture, 18x8" front on the 235/40-18 tire. How much wider do you feel he could go without causing issue of too wide a tire on a 8" wide front wheel?
I am just asking as I was really watching tire performance of various cars at Road America this weekend (all my buddies have GTR's, another heavy car but pretty much dominates all at that track) and noticed a lot of differing set ups as far as wheel width/tire width relationships.
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
I've run PSS's pretty hard on track and have never seen anything like that. Would usually start at around 34psi cold, and car seemed to like best 41.5F/40R hot. Even at lower pressures than that, I've only just barely rolled them past the shoulder tread, and with no behavior like you're seeing. Strange. I think it has to do more with the 40 aspect ratio than the tire itself, as the PSS is an ok tire on track. I think if you go down to a 35 as suggested by Mazspeed above you should be fine.
Could be something acute to that tire.... something internal failed? Consider tires consumables if you track it. Perhaps the MOST important mod next to driver mod. GL .
PSS are NOT good track tires. That's your problem right there. They're debatably the best street tire on the market, but once you put some heat into them, they pretty much go downhill quickly.
Mazspeed-it looks like OP is on the factory wheels, and for the sake of this picture, 18x8" front on the 235/40-18 tire. How much wider do you feel he could go without causing issue of too wide a tire on a 8" wide front wheel?
I am just asking as I was really watching tire performance of various cars at Road America this weekend (all my buddies have GTR's, another heavy car but pretty much dominates all at that track) and noticed a lot of differing set ups as far as wheel width/tire width relationships.
To go to an 8.5 front with a 245 tire will work well. I am not a fan of tossing bigger rubber on stock rims, and the rims and tires from the factory while ok for the street, are painfully narrow for such a heavy/powerful car on the track. 8.5 with a 245 tire that is good for our weight cars. This means no R888's as others have used.
Now here is another trick you can do. You can get the wider rims and use the same tires and you will have less roll over. .5 inches is enough to make a 235 tire flatter and won't cause the casing to roll nearly as much. It's still not ideal, but the first thing you should do is change wheels.
Your tires are trashed at this point so get those too.
Rule of thumb, when you get wider tires, you MUST get wider rims. You can get away with it on 3000lb and under cars, but you can't on a car that has as much weight as the C63 and as much power. Technically we should be running a 275 front tire and a 305 rear on the track, but there is not enough space for it.
The front tires weren't new, and they'd seen a smaller track before, I think. However, they had tons of tread and less than 5,000 miles on them.
Just a thought, but I wonder if the tires I got from Discount Tires are the exact same I would have gotten from a Mercedes Dealership? Perhaps some cut corners shortened the life of the tire? Just a thought.
In the end, I still love this car, but I think saving up for a third car with two fewer seats is in order.
Sure, I hit the rumble strips, but not the concrete. Also, both front right and left are identical, so I don't think this is a case of hitting something and breaking the sidewall.
Further, the AMG Academy guys were hitting the concrete with no damage the week before.
Well, this is embarrassing. I pulled my receipts and the tires had a little less than 14,000 miles on them and are over two years old. While I'm still surprised they gave away like they did, I would have put on fresh rubber if I would have realized they were that old. Geesh. They've seen two winters and several track days.
I've run that track many times, with PSS, Hankooks, Potenza RE-71R's and I have not experienced what you did. I hit the rumble strips with all of them, lap after lap, and no problem. It seems you had an anomaly.
It's the 14k thing that seems problematic. I don't think I've surpassed 6K, just on the street. Before you go out next time have some (much) fresher tires, fresh brake fluid, and track ready (street/track) pads.
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
By the way, Mazspeed you were totally right about the Dunlop Sport Maxx Race's having soft sidewalls. They were awesome when brand new, but my fronts did the same thing as here after my last trackday (ran them too hard at too low pressure). They're totally done now - I tried to get a couple laps out of them at NJMP last month and they were almost uncontrollable. Have PSC2's on order in 255/295. That's the fix.
check out falken FK453s they have a pretty stiff sidewall ...i've been using these tires ever since i bought the c63 and they are amazing ...I tried the PSS's once ...they are ok ...i had a lot of tire spin with them. With the falkens you won't get much tire spin (for the guys who like to chirp 2nd/3rd gear) it just launches hard
for some reason people hate the falkens though, i have no idea why...they last a long time too. The PSS i had lasted <6 months ..while i can get a year (20,000KM) easily out of the falkens with hard street driving
I've not run my C63 at CoTA yet, but I've run my CTS-V out there more times than most people can count.
I had the same issue with my PSS when I ran them on the V.. almost exactly the same result.
Issue? Tire pressure was too low.
I had to run mine (on the V) at 45-46 cold. Once I realized that.. I bought race tires The PSS's even with 275/40/19's I was running were at a loss for decent traction, likely because they were basketballs at that point.
A few upgrades later..
And the sound... (watch the guy on the right... 1.. 2.. race cars... then my V... heh)
05-01-2016, 02:32 PM
The PSS's even with 275/40/19's I was running were at a loss for decent traction, likely because they were basketballs at that point.
