Scraping sound, then tyre blowout - PeachParts Mercedes-Benz Forum

pentoman · #1 02-19-2007, 09:09 AM

I recently did a track day in my 190E 16v, which was very enjoyable. However, towards the end of the day when I was going more quickly I had an unexplained rear tyre blowout.

I threw the car into a left hand band rather quickly, and the bend had a slight compression dip. In the dip something at the back of the car made a scraping sound. I think something grounded because of the compression and the fact I was turning hard. A couple of seconds later, the right rear tyre (the one on the outside of the turn) blew, luckily I kept the car stable and didn't spin or hit anything. But it was very scary as I was doing about 65mph and accelerating fully in third gear. The sidewall of the tyre is split and there's a mark on the suspension link, but that's probably because I had to drive for a while on the flat tyre to get to the pit in lane.

Please see here for photos, I don't have a photo of the tyre to hand:

http://pentoman.blogspot.com/2007/01/track-day.html

Please help to explain this, I'm a bit scared to go back on track now in case there's something wrong with the car which is causing the tyre to blow.

lkchris · #2 02-19-2007, 10:23 AM

Sounds like oversized tires rubbing bodywork or suspension.

pentoman · #3 02-19-2007, 12:38 PM

Sorry, forgot to add that wheels, tyres and suspension are totally stock. Even the tyres were close to factory - Pirelli P6000.

Attached are the photos. You can see in the first photo, the mark where teh tyre rubbed the suspension - I assume merely from driving around the track on the totally flat tyre.

Parrot of Doom · #4 02-19-2007, 05:09 PM

I'd put money on a faulty tyre. If the geometry of the car is correct (verifiable with a laser geometry check), and the suspension is doing it's job, then theres nothing else it could be.

Bear in mind that it could have been a bit of plastic bodywork on the circuit. You'd be amazed at how much crap falls off on circuits.

pentoman · #5 02-20-2007, 04:00 AM

Quote:

Originally Posted by Parrot of Doom

I'd put money on a faulty tyre. If the geometry of the car is correct (verifiable with a laser geometry check), and the suspension is doing it's job, then theres nothing else it could be.

Bear in mind that it could have been a bit of plastic bodywork on the circuit. You'd be amazed at how much crap falls off on circuits.

Thanks, that gives me a bit of confidence.
I've checked the geometry the old school way when I first got the car - apart from a little too much camber at the rear it's pretty close.

It's just that scraping sound that keeps haunting me... should a 16v's suspension bottom out on track? I assume the rear SLS is fine - it rides smoothly and sits correctly (as opposed to sitting low and riding hard which I believe are signs of badness).

t walgamuth · #6 02-20-2007, 04:56 AM

that form of tire failure doesn't look as if it could be anything but a failed tire.

there are no marks suggesting a rub before the blowout.

the other mark, i agree, looks to be from the flat tire rubbing.

i would think of a different brand of tire, i think.

of course the mfgr may replace the one damaged tire for you in the mean time. but if it were me, i think i would be wanting something else.

maybe a michelin.

tom w

Ara T. · #7 02-20-2007, 04:58 AM

Wow, sidewall split huh. What is the speed rating on those tires.

Parrot of Doom · #8 02-20-2007, 05:42 AM

I had a tyre blow in exactly the same way, by running up a shallow kerb at speed (to avoid an accident) on 18" rims in an Audi TT.

I wouldn't be surprised if the scraping noise was the tyre running flat and the rim scraping the tarmac.

pentoman · #9 02-20-2007, 09:05 AM

I think they migth have been H rated, so only 130mph but I've never been over that. Max speed on this track was ~115 when really going for it.

Also, the track is clockwise and the tyre that went was the inside rear - so the tyre probably sees very little load over a lap. It was never warm when I came in to the pits.

I'm 99.9% certain the scraping noise happened before the blowout. The blowout was very obvious and noticeable! The noise happened in the turn as the suspension compressed in a dip. The blowout happened as I was accelerating out.

Definitely getting a different tyre brand!! And taking it easier on the car too.

t walgamuth · #10 02-20-2007, 07:26 PM

yeah, right!

that would be no fun.

tom w

david s poole · #11 02-21-2007, 09:51 AM

get rid of the other three pirelli tyres.those 6000 series are well known to me for having dry rot in the side walls[and doesn't it look like a side wall failed?]

MAF · #12 02-22-2007, 12:40 AM

I am thinkin that you bottomed out, on low air - and the bead came loose on the tire, flopped around , just a few times, and maybe you heard it hit the body, when it finally split.Jaguars run P6000's, and you are not too heavy for the tire.
I would look at the DOT number , on the sidewall, and date the tire to see how old.I read an article in Road & Track sometime ago, that said a tire looses 90% of its flex after 2 years.I bet not the tire, but the age.When you hit the bump, it didn't flex = instant disaster. .02 Mark

pentoman · #13 02-23-2007, 11:57 AM

Thanks all

Many are saying bad things about the sidewalls of these Pirelli 6000's... I guess we should steer clear.

I now have a new pair of Toyo Proxes T1-R on the rear. However, I swear that the back of the car is wandering. When the tyres were done nothing was noticed to be wrong with the car. I pulled off the motorway yesterday because at 85mph if I turned the wheel a bit quickly the back end felt like it was wandering/rolling a lot, I was scared it was going to skid out.

I will give the tyres a little while, perhaps they just feel different or it's because they're new? The ride feels and sounds normal, if something was broken I would have thought I would notice from the ride.

Hirnbeiss · #14 02-23-2007, 03:07 PM

How about low pressure causing the outside rear tire to bulge inward on the turn to the point where it rubbed on the track rod and blew?

davidmash · #15 02-23-2007, 03:42 PM

Not sure about the tire part but the wandering rear end sure brings back memories. Have you changed out any of the rear control arms? Mine wewre worn out and the rear end was wagging around like a tail on a dog. Scare the crap out of me a few times. Once I changed the links out and had it aligned, all was better.

I have never seen a tire split at the bead though. I'm with the other guys on tire failure.