Oddjob

A guy I work with likes to take his corvette out to some of the various open road races around the country, like the Silver State Classic in Nevada.

I was talking to him the other day about accidents at these types of events. Sounds like most are caused by tire blowouts, and these incidents usually end up as big accidents, to include fatalities. Because of this, he said that the event staff will tech and re-tech tires and disqualify cars if the tires are over 2 years old. He said his tire pressures will build up to 20 psi higher hot than cold (starts with 30 psi, and it will get up to 48-50 psi hot).

I have been around DEs and Club Racing for several years, and I don’t ever recall a car on the track having a complete blowout where the tire flew apart and the car lost complete control. Ive had a tire go flat going down a one mile straight away and I took the first turn at 130mph with a deflated outside rear tire. It wasn’t fun, but I didn’t lose control and the tire did not come apart. Ive heard of others having tires go flat, but I just don’t recall hearing of major accidents caused by tire failure.

Now Im curious about how/if/why open road racing is harder on tires, causing more catastrophic tire failures than closed course racing. Yes, the sustained speeds will be higher on an open road race, but the corner forces will most likely be quite a bit less than on a closed circuit road course. And I would think the corner loads and friction would heat a tire up quicker and be harder on the sidewall/structure, than straight away higher speeds. Incorrect?

Whats the word from the oval at Daytona or the Mulsanne straight at LeMans?

Laura

Tires have been a big concern for the Silver State Series. The accident that the Youngs were involved in a few years ago really opened peoples eyes at how critical tire pressure and tire temperature is. Carl has always been aware of these things and had talen extra care after a blowout the month before, but tire failure is what caused this accident. They reviewed the in car camera many times trying to see if he hit something or the tire just let go. I do know that one of the RUF cars was in our shop soon after that to fine tune the alignment and corner balance to insure that everything was optimum to keep the tire temps down. It did make a difference at speeds at 170 - 200 mph.

Roland should pop in here because he has done extensive research on this.

38D

It happened to a very good friend of mine at an event.

Joe Weinstein

I don't think it's an issue of closed-course vs. open road. I think it's that fewer folks will be
running closed-course events on greater-than-2-year-old tires. Closed course events will
naturally kill tires from wear, long before they suffer the long-term brittling and degradation
from ozone and old age. Open road events and any other typical public road driving may
not cause enough tread wear to force new tires. If some car nut has a primo muscle car
that he almost never drives hard, but brings out once a year for a high-speed road bash,
the tires may look new but after three years it is as stiff and arthritic as Katherine Hepburn,
and spinning them up to 200mph is asking too much of them...
My 2 cents anyway....
Joe

earlyapex

My thoughts:
Open road courses may be tougher on tires than closed circuits such as race tracks. This would depend on the road surface and route of the point to point corse. For example, HWY 1 between Big Sur and Carmel Highlands is a very twisty bit of asphalt. The cars during point to point races such as the Silver State Classic likely achieve higher speeds for much longer time periods than on a race track where the straights are relatively short. I also suspect that there is much more debris on an open road and it doesn't have to be very big to puncture a tire. You also have to take into consideration that a road is taller in the center for drainage so you must deal with several camber changes as you enter and exit a turn.

I've seen one catastrophic tire failure at a DE this year. Doug Gale (TrackMasters) had the side wall separate from the tread on the left front Hoosier RS3S04 that he had on his e36 M3 at Laguna Seca. He said he had a strange feeling in the steering wheel as he passed the start finish and fortunately he was able to gather it up by turn 2.

DrJupeman

I had a tire fail at a DE in my departed GT3 Cup, put me into a concrete wall. Not fun.

DrJupeman

Btw, here's the video of my tire failure as seen from a pursuing 993 Cup.

GT3 Cup Tire Failure

Tire failures at 120 mph in a turn can ruin your day..

Jarez Mifkin

I was at Road Atlanta back in the early 90's during the IMSA GTP when the two Nissan GTP cars had tires blow going down the back straight. The first was Chip Robinson, the tire blew just before 9 and sent him spinning down the straight into the 10' hight dirt wall which I was standing on. This was when the track had the infamous 'dip'.... His speed was probably close to 180 when the tire let go. The second was Geoff Brabam driving the sister car to Chip's...His tire let go after he started going down the hill and he spun off and hit one of the corner worker barriers, this was when the corner workers stood level with the track behind a gaurdrail with tires in front of it. It was rather freaky to see a car come barreling down straight at you at 150+....I had ran probably 20' away from the track by the time Chip's car impacted, it covered our entire campsite with red clay. Scary.

DrJupeman

Btw, a lot of folks like to blame the user for these failures as I suspect it gives them a "won't happen to me 'cause I'm more careful" feeling. Note that I had just checked pressures on my tires and visually inspected them before my run. **** happens and this sport can be unforgiving at times.

JackOlsen

I'm surprised you haven't come across incidents caused by tire/valve failure. I've seen a bunch.

Cars in those straight-line, try-to-maintain-some-predetermined-average-speed events are often very lightly prepped, and the drivers only do it once a year. (Some are very well-prepped, with good drivers, of course.)

I personally don't see the appeal at all. To me, racing's about going faster than the other guys.

DGaunt

In addition to the point made about age, which is VERY important, heat is probably the big factor. street tires rolling at sustained high speed for some time can fail in the belt area due to heat buildup. I'm thinking that the silver State and others have sustained high speed runs that have the tire running triple digit speeds for much longer than the sprint races we see in most PCA applications.

FixedWing

I too think it is all about heat build-up inside the tyre (and not just on the tread surface). That's why track usage doesn't seem to be a problem even though the pressures are much lower.

Interesting that we don't have more blow-outs in Europe. Maybe because People are driving faster more of the time and so tend to take better care of their tyres and wear them out more quickly?

Having said that, I have had a tyre failure at speed. I had an instant's warning at 230 km/h before it let go completely at about 200 km/h. It was a straight-line and the tyre stayed on the rim so it was no big deal at all. But I also think my tyre failure was not the "normal" type of failure. I could see signs that made me think the tyre might have been run low on air at some point in its past (before I owned it).

I do think a lot of it is about mounting them properly (and only once), taking care of them all of the time (especially never running them low on air) and just looking after them. I also think that there are more than a few manufacturing defects coming from the tyre manufacturers. I suspect it isn't that easy to make consistently perfect tyres.

Stephen

pig4bill

The word is they are using racing slicks, not street tires.

BTW, if your friend's tires are gaining 20 psi maybe he should consider nitrogen.

As for Euro cars not blowing tires left and right, they are probably not sustaining 180-200 mph (300 kph+) mile after mile on hot Nevada pavement.

JayM

In the ORR events I have attended, the big-iron guys (and any of the rest of us with sense) all run new tires, typically shaved, heat cycled, and nitrogen filled, with tire temperature/pressure monitors. There is always a lot of discussion about why the tire failures occur, but the ones I am aware of generally get traced either to faulty construction (that's why you go with shaved tires-less mass to break a weak tread block loose at the high-g forces generated at those speeds) or picking up debris from the road surface. These events are run on wind-blown two-lane rural roads, not carefully groomed tracks, and while the course is inspected and obvious debris is removed, it is impossible to manicure 90 miles of road and keep it that way all day (anything loose will tend to fly off at 200 mph, and create hazards for the next guy). Tire/valve problems from faulty installs have occurred, and there is always a concern that a tire has picked up a nail which is embedded in the tread at the start of the event (may have been there for days, or perhaps picked up on the way to the starting line). At speed, the centrifugal force expels the nail, and now you have a slow leak. As the air pressure falls in that tire, the heat starts to build geometrically, and catastrophic failure is not far away.

And BTW, I would put the "20 pounds of pressure increase" in the same category as the story of the 20 pound bass that I almost landed last week.