BoostedEBZ06

I was wondering if it's safe and if flat spotted tires affect traction at all.

Last time out at Thill my ABS went inop due to wonderful Russell SS lines I ended up locking up the tires once for a couple seconds, flat spotting the fronts.

I have a vibration between 50-60mph, is it safe to run them and will that affect traction at all?

The tires have plenty of tread left so maybe I can wear the flat spot out?

I have an extra set of 18" wheels to run a square set up, so was wondering if I should go ahead and drop $1000 on tires or get my new seat.

Thanks.

FuriousDonuts

I can't speak to the traction issue, but my experience is that confidence goes out the window with a flat-spotted tire. It's hard to tell when you're at the threshold when the whole car is shaking!

IMO, it's not worth it. The lack of feedback may be even more dangerous than just loss of traction. Maybe keep them around for test & tune runs so you don't have to worry about using up a good set?

froggy47

You will probably cord them pretty quick if you use it that way. Then you'll need to quit & lose a day unless you carry a spare pair.

12zo

Sounds like they might be bad enough to not run them on track.
I would recommend finding a skid pad.
Skid pad practice is very useful and a set of tires you are about done with can really pay for themselves on a good wet skid pad.
Make sure someone skilled is in the car with you to really help you figure out how to rotate the car.
The bonus is, it is a blast!

SouthernSon

My only experience with badly flat spotted tires happened this past summer. While racing at AMP a car in front parked on me before the start finish line for some reason. Not having ABS and a somewhat suspect brake bias, I locked up the fronts and flat spotted them down to about an eight inch patch of brite metal cords. The rest of the tires were almost full tread. I had to continue a couple of more laps at speed while the crew readied the other set. Tires held but the car almost shook apart.

ZedO6

IMHO, once you flat spot tires to the point of vibration, you're done. Those tires will find the flat spot under braking which can cause another lock when the flat spot, which now has a larger contact patch then the rest of the tire, grips and grabs...ABS may save you here, but like someone else pointed out, hard to be confident with unpredictable grip like you get from a flat spotted tire.

63Corvette

I concur!!!

BoostedEBZ06

Well that's not what I wanted to hear, let's hope I didn't flat spot the rears too!

Eek...any good way to test that?

flink

Move the tires to the rear if you can - the flatspotting becomes largely imperceptible.

It might be acceptable that way, but I wouldn't go to the track without having a new set on hand to replace them.

Flatspotted tires make an interesting driver aid - when you're cornering near the limit and the flatspot come to the bottom, the car skips sideways a little bit. So the vibration strengthens as you get closer to losing overall grip. I'm not sure I'd recommend taking an angle grinder to your practice tires though

UstaB-GS549

The flat spot has a shorter radius and if the brakes lock it will generally happen at the same location.

If you get your ABS working it will probably delay the amount of time it takes to cord the tire. Mark the sidewall and keep checking everytime you come in.

Bill Dearborn

Bill

BoostedEBZ06

ABS is working again I simply replaced the Russel lines with Goodridge and it's all good!

How do I find the flat spot? Is it as simple as looking at the tire or rolling it?

ZedO6

You should able to see it if you raise the car and hand turn the tires. If not, you can take it off and roll it and the flat spot will be obvious.

Supercharged111

LOL, I'm about to get hated out of this thread. I flat spotted my right front last year and expressed concern. The guy I borrowed it from said it'd be fine after another race, and it was. Mind you this was nowhere near the cords, but it worked itself out.

BoostedEBZ06

Interesting i was wondering it that was possible.

I'll see how bad the flat spot is tomorrow and decide from there.

Supercharged111

I'm not going to lie, initially it was annoying as hell, but I flat spotted it in my comp school race and proceeded to take 2nd place in my 1st real race. Admittedly, there was a 3 car tangle that I blew through and just ran for my life and held on, but by the end of the race I'd forgotten the right front had ever been flat spotted. My car runs around -2.5* camber, so it tends to only flat spot the inner half of the tire, so that much less to un-flat spot but I'll be damned if it didn't work. This was on RA1s that were cycled out and about done, but by the end of the weekend I corded the shoulders and not the center meat.

the blur

I once flat spotted 2 new kumho's. I wanted to get them shaved, but no one would shave them once they touched the ground.

The problem is, it shakes apart the car, and destroys everything in your suspension. Your rod ends, shocks, springs, body panels. Everything shakes to death, including your body.

I sold them to a drag strip guy for cheap.

BoostedEBZ06

Welp finally got around to swapping the lines today and the only tire that had a noticeable flat spot was the left front the tread in one area was significantly lower than the rest of the tire.

The rest looks good I could tell where the lock up was on other tires but no flat spot or tread height difference.

So looks like only two new fronts are need which isn't a big deal because I was going to run 18s all around anyway.