madryan

did anyone ever "chirp" from 2nd to 3rd???

i was at a light. i took off for the highway with the esp off, the car easily "chirped" from 1 to 2.
then i got on the highway, and reaching about 50 i switched to 3rd and the car "chirped" again.
the car easily got up to 80. then i slowed down a bit for the lovely ny traffic.

i was wondering if the road was wet or maybe some loose gravel was on the road, but i don't think there was.
let me know if any others have experienced this, b/c i never thought this car would be able to do this.

thanks,
ryan

todd

Well if you have the 17 inch C7 wheels with ContiSports they will definately chirp on 2nd to 3rd.

I noticed that the air pressure in my tires is 40 PSI front, 44 rear.

In the rain you will be activating ESP through every intersection as the tires slip on the painted crosswalks.

In the dry and in the rain elsewhere they are a solid rock, track on rails dream ;-)

MarkL

You mean this is what you "found" them to be, or you set them to that pressure? When my car was delivered (C240), the tire pressure seemed high at 40psi. I lowered it to slightly higher than the recommended 28 front, 30 rear. 40/44 will give a hard ride, no?

todd

Yes it gives a harder ride and the tires track 'rain grooves' on the freeway more, but cornering is WAY improved.

I think the sticker with recomended pressures are for stock (GT?) tires, not the ContiSports mine came with.

I noticed also, that after bringing the car in for the oil change at 4K miles, that the valve stem caps were removed, by the smudges in the brake dust on the wheels.

So I checked the pressure and they were lowered by the mechanic. I raised the pressure (using a great meter from Perfomance Products, analog brass, much better then the digital I used to use) back to 40/44.

When the car arrived from the original dealer (not the one that performed the oil change) this is the pressure they were at as well.

The markings on the tires say max PSI 50 pounds.

MarkL

Interesting. I wasn't sure whether the factory set my tires at 40psi, or the dealer. When I lowered them, I wondered whether they were set higher for shipping (more stable on the ship?) I also looked at my Goodyears that came on my C240, and they said max was 50 psi. Maybe I'll raise them up a little more.

Flashman

Higher tire pressure will give you a firmer ride with less side-to-side sway in cornering (tighter turn-in) and lessened chance of rim damage.

However, lower air pressure will give you a smoother ride and better grip.

Usually I inflate my cars to 3-5 PSI above manufacturer recommendations, since I feel most manufacturer's under-inflate their tires for the smoothest ride possible.

Rick

Iceman's C230

Well, i tought if you chirp into 3rd that your not getting any traction on the tries. Try lowering your PSI on the tires.

DtS

The tires are over-inflated by the manufacturer just to prevent "flat spots" during long transports. Usually the dealer leave it this way as long as the car is in the show room.

mbtech208

The tires are set at 50 psi during shipment. As soon as they arrive at the dealership, the technicians set them to manufacturer's specs during the PDI (pre-delivery inspection).

todd

Thanks DTs and MBTech, that makes perfect sense.

sk-mia

I thought that overinflating or underinflating the tires will cause that the tires will wear excesivelly at center or edges respectively. Therfore, I assume it is best to inflate them to the car's specs.

However, if one is to race the car, overinflating the tires will result in fractionally better cornering. This is why they do it on race cars' tires. But they get new tires for every race at least, if not changing a couple of sets during one race! Of course, these tires are much, much softer than the regular street tires, but still I would not be willing to change my tires frequently (and certainly not per one "race", he, he) just because I overinflated them for performance, which, by the way, would only be a marginal, yet expensive handling improvement.