Spin9k

What all the more surprising about the OPs problem with his tires is that he's experiencing it at all. The RX-8 is not exactly featherweight, but in DD form at only ~3000lbs stock, it IS one of the lighter cars (stock) typically seen at HPDE events. Meaning it is pretty easy on tires, brakes, etc. due to its weight and lack of power.

For the OP to shred tires means one (or more) of several things: 1) no air in tires, 2) he drives like a maniac, 3) defective tires/the tires are complete crap for the task at hand or on a performance car in general. I doubt he drives all that crazy or forgot to check pressure (correct me if wrong etzilon ) so the Kumhos themselves.... And really Kuhmo? Not starting a flamefest on Kumho lovers, but it is a (very) budget Korean/Chinese made tire after all.

My only experience with them was with some Ecstas on another car when I got it used, and they were loose, limp, under steering, howling carcasses with no redeeming traits to like. Replaced w/everyday Michelins and the difference was night and day, suitable comparisons fail me as there really is no comparison.

All this talk of HPDE tire adjustment, advice etc., ONLY makes sense and provides benefit if the tires themselves are up to some semblance of the task in the first place and CAN be adjusted with some benefit. Best for the OP to get some decent rubber on, try them on track, then ask his questions once he feels the car working under him as it was designed i.e. with rubber under it at least as good as the OEM Bridgestones/others Mazda supplied.

The thread will still be here

dannobre

iTrader: (3)

My only addition to your post is to buy a proper tire pyrometer. Tire surface.temps from a laser are poor indicators of tire temps. The outer surface cools off way too fast.for them to be accurate. The proper pyrometer measures tire core temps that are more stable

etzilon

Wow! I never expected so much attention :-)

Let me answer some of the questions:

Why Kumhos? Because. When I bought the car, it had Kumhos. Before tracking the car, it is what the dealership had. Decision by default. During previous track weekends, the tires did well; they looked as if they had been pushed harder than street driving but they survived. I like to believe my driving has improved and my tires are giving up but I am my worst enemy, so that's why I posted the question.

Will you continue buying Kumhos SPTs? I'm a cheap bastard, but no. They worked. They don't now as I track the car more frequently. As I mentioned previously, I'd rather have a set of wheels for track with better tires (someone recommended Nitto NT05 and they look good to me, pricing-wise).

Why 35.5/30.5 psi? Chalk. I chalked them and that's what I came up with.

Did you remember to check pressure regularly? Yes. Before every session as part of my pre-session ritual (check oil, torque lug nuts, etc)

Do you have a pyro? No. Alien technology to me. When I understand why I need it, I'll get one.

Were you racing? Yes, with myself. Just trying to improve my times.

Spin9k

Nice to have attention, yes? No worry, you're just learning like everyone is, you'll be fine FYI, the pyro is relatively hard core, cost $$, and is very accurate. The surface gauge isn't as accurate, but much cheaper and quicker to use if you're only nominally adusting pressure for the next run.

Galen Darkmoon

I always love this discussion on tires.
When running Hallett on a good day we have the car come off the track with her tire press at 48lbs front and rear. Barb really hits the corners well and any less and the tires will roll to the sidewalls, but at that temp they wear well and stick like glue. Anytime she does slide the car in corners it's a straight up four wheel drift sideways. All we have done to the suspension is add RB sways front and rear. OH the tires are Nitto NT-01 245-40-18 We start em out at 36-38lbs then hold em at 48 after they are hot. Everyone tells us thats to hi but weve had others check the roll marks at the track then agree with us, go figger.

04Green

iTrader: (1)

@ OP..

Sounds like you are on the right track.. I would suggest care in torquing lug nuts before each session, it is easy to creep up the torque with hot wheels. You will know when something breaks. The PCA folks say check cold, start of the day, and leave them.

etzilon

@04Green: I start my 'ritual' 10 mins before going out so the car has cooled down from the previous session.

alnielsen

iTrader: (4)

Track Days are hell on new tires. Full depth tires hold heat and the tread will squirm while cornering causing more heat. You are driving basically under race conditions and racers, in street tire classes, get 2/3rds of their tread shaved off before taking to the track. This eliminates this problem. Running full depth tires is an open invitation to have an $800+ set of tires turn into junk.

etzilon

@alnielsen: Are you referring to shaving off 2/3rd of the outer tread or from everywhere (including center)?

I understand this will extend the life of the tires as it prevents overheating, but wouldn't this reduce the life of the tire due to less tread?

Do slick tires suffer from the same too-much-treadness?

alnielsen

iTrader: (4)

Yes, it will reduce road life. That is why many have a set of road tires and a set of track tires.
In road racing the term slick isn't used. That is a drag racing term. True road race tires, while treadless, are made with different compounds for different track conditions. These conditions will, air & asphalt temperatures determine what compound you will run for that day. If the air temperature drops, a sticker compound can be used.
You will find a tread pattern in rain tires of course.

etzilon

That doesn't sound budget friendly at all! Darned me and my hobbies!

Thanks, alnielsen.

bse50

Track tires also suffer less from heat cycles. Sure they will degrade but it's nothing compared to what happens to "performance" road tires. Some become simply dangerous after a couple of heat cycles, especially with cold tarmac or rain.
Having a second set of tires really makes sense if one wants to track the car even just 4\5 times a year.
Wait to see the bill for other wear items

Spin9k

If you want budget friendly - Nitto NT01s are a good example of decent 'budget' race tire (that isn't a true race tire per the tread def above) - but is still a D.O.T. approved R-Comp tire - it starts w/6/32" tread but rubs that off for the 2nd half of its life. Guess it's half a race tire dunno - for instance you can drive to the track with these on no problem. Personally - I have driven 400 miles to track w/them... sometimes in the pouring rain. Still here. But I would never do that with my BFGs, totally different animal, track only.

If "5" is a performance street tire, and "11" is a race tire (eg. BFG R1 or Hoosier), the NT01 is an "8-9" roughly. Very acceptable for track use, and very convenient, and light years ahead of a street tire.

etzilon

Oh boy... I might need to start a new thread.

Arca_ex

iTrader: (10)

You need an alignment is my guess... on 275/40/17 NT-01's they were right on the money at 37PSI. 48 is ridiculously high, if you need that much pressure in order to not roll over onto the sidewalls something else is wrong. Anything above 42PSI on those things and I had NO grip compared to running at 36-38 range.

Galen Darkmoon

I told you I love these discussions, and not to start a flame fest but you are wrong in this case. We are there and have track pros helping us.
In fact here is 1 lap at the track, you tell us what we are doing wrong.

http://s213.photobucket.com/albums/c...theMustang.mp4

wrightcomputing

iTrader: (5)

I would definitely get an alignment done it is relatively cheap and can have a very positive affect on the handling of you car.
You can do it yourself which will cost nothing. I do mine myself after talking to lots over very helpful guys on here. It might take a couple of hours the first time but after that it will take less than an hour.

wrightcomputing

iTrader: (5)

If you want my opinion I think you are a little late on the brakes and you are overloading the tires by cornering too quickly causing them to screech rather than sing.
It is obvious that you are a pretty good driver though and better then most on the track with you and your line is very good.

Galen Darkmoon

Thank you very much, and now for the rest of the story.

The misses is driving a 6 spd auto with upgraded rotors and cobalt pads :she is still getting used to those: The mechanic who takes care of her car is a master rotary mech in kansas "took 3rd in their national mech trials?" does this on the side for fun.
The pres of nasa central saw her drive and asked her to join nasa and do any tracks in the midwest class 1 or 2 her choice, no training classes.
Not bad for an old woman "44"
It now has an s/c in it :a big thx to all the masters in the pettit forum.
and btw, the mech above makes sure its aligned prepped and ready to rock.

I guess I'm saying is what was posted earlier. What works for me may not work for you. We will get there.

Arca_ex

iTrader: (10)

I guess I don't really know how I'm supposed to gather information about your tire pressure preferences from an extremely low quality video with no telemetry?

Galen Darkmoon

well I am truly ashamed arca, must really suck to admit when you are wrong.

Arca_ex

iTrader: (10)

I'm just curious more than anything as to how you're getting them to roll over onto the sidewalls at anything below 48PSI.

Then you provide a poor quality video with no real quantitative data and tell me I'm wrong lmao.

All I really wanted to know is what your alignment is, how much your car weighs in comp trim, and if you have any telemetry to see how many G's you're pulling in corners.

Galen Darkmoon

My apologies then, no I don't have that info I leave that to the guys who do. All I can say is we tried the lower pressures all the way to what we run. All I really meant to point out was the differences in cars and driving styles, Barb driving a slower auto she comes into the corners as hard as she can. Wright commented on the tires squalling and he is correct, she is right on the edge of breaking loose and sliding off the track. She went thru the first set of tires in no time till the semi pro racers at the track broke her of trying to be the drift queen on hi speed corners.

swoope

iTrader: (5)

thanks for not trying to be an ***. but walk then run... i run hpde 3. and i am fine with that..

i know the good advice that i got on the way.. and as i read most preformance tire manufactures tell you to do..

39 to 40 psi hot is what your are looking for.. for my car if i start in the morning with 34 front and 30 rear after my first session i am with in one pound of that. depends on track and conditions, but it has been consistent over the years..


btw, my first event was on the kumho spt.
to the kuhmo note ran them in a couple 2 hpde events. went to the star specs as a dd driver track event tire. got me to hpde 3. then i came across a set of oz superlaggras from an race team and tire rack was closing out the reo1R.

i have not looked back..

as i mentioned above kumho spt and the kook v12 will do fine on the track also, but later it will chunk..

but really if the op ran the event on stock tires he or she would be fine..

the car stock should get you through hpde 2 just fine..

the rest of it you should pick up as you go along..

and if you need track tips, look in the track section and a thread started about alignment by trackaddict.

lots of good info in that thread..

as hpde not being a competition i am the king of that!!! glad you are running in 4. but really it is just you are passing or in the way.. last dyno my rx8 made 195 at the wheel.

but running with chin motorsports at sebring i am the miata on a really tight course. running with a bunch or rx8s with good drivers..

hope that makes sense.. have fun, dont do it in the streets..


beers

Galen Darkmoon

Swoope: have fun, dont do it in the streets..

A few dollars for a track day pays for a multitude of tickets and Ins premiums anyday