max pl

Hoping someone here has experienced the same issue and has a suggestion on how to remedy.

Had another annoying experience with my Hoosier tires two days ago.

Began day 1 on 13 HC tires and the car ran great all day with no issues, matching my pace last year. I had new ones mounted that afternoon hoping to run even faster and ran 1 session and had great grip, but pace was a bit off for whatever reason.

Start day 2 on essentially new tires and the first session went well. Second time out I begin to experience slight vibration and come in to check the tires. I remove both front wheels to inspect, find a good bit of rubber pickup, and shave it off using my heat gun tool.

Went out again and the car felt fine for 5 to 10 minutes and then the vibration returned.
I called it a day mid morning as this was reminiscent of my last time out there with new R7s, and I didn't want to continue to waste time until I thought about the problem.

I contacted Hoosier this morning and was immediately told that pickup is largely due to the tires not being warm enough. Others have told me that the simple solution is to scrub the pickup off with threshold braking or to drive faster, and I guess driving faster is the answer as that’ll put heat into the tires, but this contradicts my first day out with the older tires as I had zero pickup that day despite the same tire pressures/conditions.

So is the issue that I’m starting my day with too low of a cold pressure (26 psi), targeting 34psi hot, and that’s resulting in me not getting the tires hot enough? The Hoosier rep told me to target 40psi with a 3600lb car, which I guess will be the next thing I try, but my experience with 34psi has generally been positive.

Heading to LRP this Monday and will start the day at 29psi cold and hopefully get to 40psi hot quickly enough to scrub the pickup off. I went from 26psi cold to 38psi hot at WGI in 15 minutes on the older tires, but doubt that will be possibly at LRP.

Frank 993 C4S

What kind of car? Pickup on front or rear tires or both? How much toe are you running in the front? I have only ever encountered this with too much front toe and on a car with tires I struggled getting up to temperature because they were too wide for the application (low hp vintage car).

max pl

It is an F80 M3 with pickup on all four, but mostly the front tires. Running zero toe.

Speeds5

Play with your pressures. Try bumping it up a couple of PSI hot and see if that helps

GC996

They will pick up plenty of things. You just gotta drive them hard thru a couple of turns and they will clean up.

Also keep in the back of your mind that they are much grippier when hot versus your normal 200w tires. What this means is that you can stay on the gas longer and brake harder. If you are at a fast track under this heavy braking you may experience slight tire slippage on the wheel depending on the wheels you are running. This ends up upsetting the wheel balance and will cause some vibration as the day progresses.

This always happens at Road America because of the speeds and therefore extremely hard braking. Dpesnt happen on the smaller tracks. If it's a big event at RA, there is usually someone there to pay to rebalance the tires. If not, it pays to bring a couple of sets of wheels as a just in case.

Hope it helps.

Jas0nn

Adding pressure (all else equal) would usually decrease tire temp. Hoosier's recommendations are usually quite a bit higher than what most of us have found works - so their hot target doesn't really surprise me.

I don't mean this to sound rude, but are you driving the car hard enough? Are you taking advantage of the extra grip the low HC offer?

If conditions are the same/similar, you should be going measurably faster on a sticker compared to a 13 HC tire. For example, at my last event at Summit Point, I saw a 2s difference between practice on 6HC tires and quali on stickers. (Same day, no setup changes). The difference between 13HC and stickers should be even bigger.

RobT 394

in my experience, every set of Hoosiers is different. Some are good, some less good and some are epic. All of them slip on the rim making it a good idea to mark the valve stem location with every new set. First session on new set of tires and the tires rotate on the rim. Every time. Balancing lasts about a half session in my experience. Makes me wonder why to even bother with it. Point being. Get to know the car and the vibration. If it is high speed then determine if it is front, rear or both. Really try to understand that feeling so you know the difference between tire pickup which should vibrate at all speeds, balancing, or if you have a problem. Sometimes one can get so used to the vibration they miss a real issue. That is what you want to watch out for.

As for pressure, what Jason said. Go with what provides grip and not what they recommend. Would be surprised if was not in the 32-34 range.

GC996

^^^These

LuigiVampa

I started racing with Hoosiers and no use them again with my 911Cup.

I agree with Jason in that you can scrub a fair amount of pickup if you drive hard. Sometimes you get a little pickup, which causes a vibration, which makes you drive a little slower, which gives you even more pickup. Rinse and repeat until you have huge marbles stuck to your tires.

Also, while there is rubber all over most races surfaces, it is offline where you find the most. Are you trying to avoid those heavy buildup areas?

max pl

This is my exact experience anytime this occurs. I slow down due to the vibration and apparently that just adds more marbles as I'm not generating enough heat.

Anyone I've asked about this issue the past few days argues that I must be off line to get pickup, but no, I do not go off line, even when giving point bys. I force the passing driver off line. The one area I speculate has perhaps led to some pickup is the outer curb at T1 at WGI or perhaps T10; are curbs usually an area with an increased amount of rubber on the ground?

My issue is entirely caused by rubber pickup and not wheel balance as my journey with this issue started with having the wheels rebalanced countless times, double layers of HVAC tape to keep wheel weight on, and then moving to hairspray to have them mounted. All of this has led to very little slip of the tire on the wheel ruling balance out as the cause of vibration.

Frank 993 C4S

Hairspray is your answer when mounting your Hoosiers. It prevents them from rotating on the wheel.

analogmike

I get terrible pickup on my R7s, it was so bad on my A7s that I stopped using them.
Running low pressures on big tires on a light car, usually close to the lap record.
I shave off the pickup before an important session.
Also using hairspray now as my LR would rotate so much at Lime Rock that due to the vibration, I could barely see in the downhill.

dgrobs

Stay on the racing line and try to avoid late offline entries into corners. That's where the crap is. Some tracks are worse than others.

Pitt Race has the most rubber swag offline than any other track I've ever been on. Also has the best grip of any track I've ever been on. Def a direct relationship grip to crap.

I run R-7's on both cars, and pickup is part of the game with them. Eventually the pickup will get scrubbed off or it will become part of the tire as it melts into it.

Purple Crack FTW!!!!

Frank 993 C4S

Have you ever tried a narrower front tire?

Locker537

Avoid off line passes? No way! That's where a lot of the fun is.

DE is not racing, we know that - but think about this problem if you were racing. You're off line quite a bit. Obviously this issue can be managed in other ways.

If it's a temperature issue and pressure related, a pyrometer may help you diagnose and correctly address.

Personally, I find the vibrations disconcerting at high speeds but get used it once the tire sheds the rubber and the vibration stops. Essentially, you learn it's normal and accept it.