etzilon

I have tracked my car a few times (i.e. I'm no expert). I wanted to know you guys' opinion about my front tires after my last road track weekend (see attached pics).

We had a lot of seat time and I was running faster than previous track events (yet, there is time to shave off... I know it).

These are Kumho Ecsta SPT 225/45/18 on OEM wheels with factory alignment on OEM springs/dampers/sways. They saw a track weekend as new rear tires in Nov, very little use on the streets in Dec and moved to the front in Jan.

The front tires took a beating, especially the passenger side one (more left turns than right turns and faster left turns). My question is: why do you think they are falling apart? I can take any comment (crappy tires, crappy driver, crappy alignment, I'm an idiot, etc) as long as you explain the rationale behind it :-)

Thanks in advance.

speedracer2169

Those Kumhos have very soft sidewalls and they weren't meanst for track driving almost any non high performance tire will feather like that after exessive heat.. I had them on my Evo once and switched them for bf goodrich the less than 24 hours later. Your alignment seems ok not too bad sometimes adjusting the toe can correct that but I would probably recomend getting another set of wheels and some better tires like Falken RT-615 or Dunlop Direzza's Star specs for the track

Arca_ex

iTrader: (10)

They're doing that because they're garbage for the track. They're 320 tread wear and weren't designed to be driven super hard.

Try getting another set of wheels and putting some Hankook RS-3's on it for track use only.

alnielsen

iTrader: (4)

Real racers shave half the tread off their tires to get rid of tread squirm and reduce the heat buildup in the tire. You don't want to go aggressive on a full depth tire.

elysium19

iTrader: (1)

This is what's great about the internet: I was looking at these tires but saw reviews on tirerack that described this EXACT same problem. Now, I mostly just need road tires, but do 1-2 track days a year, so I stayed away. Lots of good info out there if you take your time to find it...

Bridgestones - not cheap, but work well and last surprisingly long time....

bse50

Agreed, I liked the re050a a lot. Nice on the streets, decent at the track and a good wear rate. The only problem is that they become kinda hard after a few heat cycles and this makes the compound very slippery on wet\cold (10-15°c) surfaces.

etzilon

If I am going to be spending $250/tire, I see track wheels in my future.

Spin9k

If you don't want R spec track tires (like Nitto NT01s) but do want them on separate wheels.... I'd suggest some Enkei 17"x9" track wheels (about 15lbs each vs~21 stock), and shod them with some 255/40ZR17 Nitto NT05 ~$175 (http://www.nittotire.com/Tire/nt05#overview). NT05s in 245/40/18 are my DD tires on OEM 18" wheels and they are excellent with UTQG Treadwear: 200 Traction: AA Temperature: A.

Or you could just buy them for your OEM wheels, they'll just be a bit slower and heavier.

Reasonable cost/xcellent performance/trackable

etzilon

Yup. After many days of searching/reading, I will be going for 17x9 Enkeis when budget allows; street tires first until 'the driver' can leverage stickier tires.

swoope

iTrader: (5)

yep,

lots of good info here, anything over 200 treadwear is going to overheat if you get near the hpde 2 level.. the other tire that is great till you hit the level 2 hpde mark is the kook v12.. great tire for the street and learning the track, but once you start using it hard on track.. i will chunk like the photos of the kumho..

beers

etzilon

Thanks everyone for your contribution. It sucks having to put the 3 week-old Kumhos in the dumpster but it is the safe thing to do.

swoope

iTrader: (5)

unless they are chunking a lot you can still drive them.. common sense prevails. mine showed up about 8 months later..

beers

etzilon

While not at the track, the car is my airport commuter (15 mi each way) so I'm not concerned about street driving... but they will never see the track again.

04Green

iTrader: (1)

Actually, the V12 will chunk a lot worse than the Kuhmo.. If you are tearing up the front, and not the back, you are also pushing (understeer). There is a great table on tire rack about how to mitigate understeer. I printed it and stuck it in my track book. http://www.tirerack.com/tires/tirete...jsp?techid=58& In you case, you would pump up the fronts, and let some air out of the back, keeping a safe quantity in the back of course. This will kill some of the rear traction and let the car rotate better. This is best done in SMALL steps (2 psi max). The get used to it. Changing too much at once, and not paying attention led to a cool Turn 9 dismount at Roebling. A suggestion is to just pick up 2 more Kuhmos and work with pressures to loosen up the car. You should be able to go pretty well on those tires, just pay attention to them between runs, and if they get a little hot, come in. I did not get track tires until I could chunk the fronts and rears the same. I will let you know how it goes.

etzilon

Great points, @04Green. I will post pics of the rear tires when I am back in town.

What I can tell you is that the rear tires were brand new before going to the track and the 3 center ribs look the same as the front tires, a bit less damaged but damaged nonetheless; not so much tearing on the side tread, which makes sense.

I did chalk the front tires because they looked as if they were going deep into the sidewall (a little over the little triangle shape on the sidewall), so I put some more psi on them.

I ended up with 35.5/30.5 cold @ 57F ambient. The rear pressure seemed low but they weren't going into the sidewalls (maybe that Carbing rear brace is helping?) and the car felt good and I had my best lap time (ever) with these tire pressure combo.

Spin9k

I would strongly warn you against trying to use those Kumos again or replacing the worst ones with more and continuing. They simply aren't what you need, obviously. Chunking tires are failing tires, the damage in photo #2 shows just the surface extent of the damage, not what's going on inside. Some chunking is just minor cracks in the tread, but yours tires are really losing 'chunks' of rubber. You can't see if the cords are separating as well, for example.

You'd think they are pretty OK tires reading the reviews. Though for ~$150/per I guess you can't really expect too much, esp. considering OEM tires are ~$225/per and really good tires are in the $250-300/per range each. Also many pure street tires start with too much tread depth ~11/32th, which builds up too much heat for track use, at least wo/being shaved. Most hi-perf tires start with less tread like ~9/32th or less just for that reason - heat buildup.

Tires and brakes are everything on track. Be safe, don't chance yours or others safety - get better tires!

wrightcomputing

iTrader: (5)

I would not throw them away. I would keep them maybe in future you can use them for practice autocross days or something once you get a 2nd set of wheels. I kept an old set and of tires that were odd sizes 225/45/18 & 245/45/18 I ended up needing them for a racing school when my delivery didn't come through. I used them on the front and they did till my other tires arrived. If you start racing a lot you will go through a lot of tires. I change mine 2 at a time and it seems like every 3-4 months I need a new pair.

etzilon

The reason I started this thread was to compare notes and identify whether the damage was being caused by too low/too high air pressure, poor driving, 7-year-old suspension,etc given my limited experience at the track.

Based on the many comments (thanks everyone), everything points out to my poor choice of tires (decision by default, it is what the tire shop had).

I do road track weekend events every 2-3 months; I am concerned with a tire exploding during one of the fast turns so I will be getting new tires.

40w8

I had the same SPT's, tracked to what I thought was the limit, but I have 6spd auto, and never tracked on hot days; only spring or fall.

My SPT's had nothing weird, just worn evenly.

I like to run 40-45 hot front, but I think your trouble was mostly understeer, hot day, and underinflated.

SPT's are good cheap tire, but I'm always looking for better, and you seem to need a real track tire.

04Green

iTrader: (1)

Ah,

Chunking front and back, time for different tires... I did not understand that, sorry.

@nadrealista, if I did not look at the tire rack chart, I would agree. That is the part of the table I have the hardest time getting behind. All I can say is that it seems to work, I have no idea why.

Guide To High Performance Handling

Adjustments Decrease Understeer Decrease Oversteer
Front Tire Pressure Higher Lower
Rear Tire Pressure Lower Higher

Arca_ex

iTrader: (10)

The chunking isn't being caused by the tires not coming up to temp it's because they're bad tires. Even if you would have taken like 3 or 4 warm up laps you would still have the same results.

Look at getting either Hankook RS-3's or Dunlop Direzza Star Specs, both are great tires for the track.

And with the way you had your pressures set up with the front being 5PSI higher, that's setup for even more understeer. If you want to combat understeer you need to go higher pressure in the back and lower in the front. But with terrible tires these adjustments are almost a moot point anyways.

swoope

iTrader: (5)

first off the both the tires chunk because they are out the the temp range for ~280 thread ware tires.. i think i warned 04 green about the v12 kooks. great tire for the street, but as with the khumos past hpde 2 they cannot take the heat..

as to the pressures, the answer is 39 to 40 lbs hot. to get this for a while i start at 30lb rear and 34 in the front. depends on the track, but it is a very informed start.

have not tried the kooks s3. have run through a set of star specs. if you are at that level you need to split track tires and wheels and street..

to have a set to do both ends up costing more..

bonus if you go to 17" wheels for the track. tire cost less..

beers

Arca_ex

iTrader: (10)

Ideal tire pressure isn't as easy as throwing out a number... it depends on the tires, how big the contact patch is, the alignment the car is using, the suspension setup, how much body roll you're getting, how much the car weighs, how much the tires are rolling over, etc etc etc.

My ideal pressures with 265/40/17 Star Specs and my suspension/alignment/setup is 36.5 front and 35 rear hot. But not a whole lot of people are likely to use that exact tire pressure because nobody else here has a car setup like mine. See what I'm getting at.

The goal of tire pressure is to get even wear, and therefore grip, across the entire contact patch. You want the contact patch to extend out to the tip of those arrows that you typically see on the side of the tire, and you want the surface temperature of the tire to be the same on the inside, middle and outer edge of the tire. A laser thermometer is helpful when trying to determine tire pressures for maximum grip. After finding a number that provides maximum grip you can play with the pressures in 1PSI increments usually to try and assist the car with oversteer or understeer problems. Just try to remember that it's a FINE adjustment tool.

Also it's Tread Wear not Thread Ware.

swoope

iTrader: (5)

sorry to miss type.. and not spell check..

you are in a league way above me.. i just gave smart info for people that track this car..

most of the tires on track look for a hot temp of 39 to 40 lbs.. as to lazer temps across the tire. really good info. also depends on rim width to tire width..

this thread i think was about a track day, not a i am going to win my local auto cross or i am the fasted hpde in class2. but really, i pissed away a lot of money by overheating a set of street tires on a track.

now if you want to open you own thread about how i won hpde 2 let me know.. think you are missing the point here.. this was a question about a stock car at a track event... with oem sized tires..

i have some time with oem sized tires and others on a track. and lots of other tire sizes.

most people that do track days, enjoy them.. my guess it you take it to the dick level.. hope to see you in homestead april 27



beers

Arca_ex

iTrader: (10)

Sorry, wasn't trying to be an *** I'm just trying to give him some good info so he can get the most out of his tires lol. I destroyed an 800 dollar set of street tires on my first track day way back in HPDE1 as well, we've all been there. Most of the time 40PSI hot is way too much is what I've come to find out, so I'm just giving him the tools to figure out what's best for his own setup.

Most of the people at track events here run in between 32 and 38 PSI. But again it depends on many factors and everyone has different ideal pressure settings. Try starting at the manufacturer recommended inflation level which is 32PSI cold and go from there. Another trick is to use a grease pen (the kind you write on windsheilds with) and mark a line on the side of the tire up to the tread. It will rub off where your contact patch is, if it's rubbing off on the sidewall, your pressure is too low, if there's still marking on the tread, your pressure is too high. It's just a visual aide for how much you're rolling onto the sidewalls.

And remember HPDE driving isn't a competition, I'm still N/A with only 174RWHP the last time I Dyno'd, there are much bigger fish than me in my HPDE4 sessions haha.