Shinka13

Okay, here's the situation. First, I have the stock Dunlop SP Sport 8090's. I went to Tail of the Dragon in September (great time btw), and towards the end of the week, my tires felt like they were starting to lose traction. It started taking a few corners to get the "regular" feeling back. Now, driving around here locally, it feels as though the tires have lost all the regular feeling. They break loose like never before, and get really "fun" to drive on when the temp dips down to mid 50's. Last year, I remember them not turning to hockey pucks until mid 30's, low 40's.

What my question to those of you that may know, is it possible to have heat cycled the tires enough to have changed the compound enough to harden and lose their grip? I asked Dunlop this question, and as usual, the customer service rep knew nothing. The tires are rated a "W" for speed, treadwear 280, and "AA" for traction and "A" for temperature.

The reason I'm asking this, is because I'll be buying new tires in the spring, and want to ensure that I don't do this to my new tires. (Been reading as much about tires that I can...still undecided) Thanks in advance for your help.

DOMINION

Sounds like you dont need new tires.
I have a AT. Same thing whith the rear end breaking loose on me at 5.am 50+ out road was dry.
Same thing happen to my friend he has a MT with 20's we got off the freeway off ramp he was all over the place for a sec but was ok.
So I dont get it. I dont know if the tire compound was effected when you where jamming in the twisties. As some track guys on here.

iridearocket

There is no way you heat cycled those tyres! I have taken many street tires to the track and I'm not sure I can say they even warm up. Sure if it's 45 degrees outisde, they warm up a and the grip may improve a little, but on a hot summer day, barely will the grip level change as temperature increases.

These tires have a traction of A (not AA), just like the Direzza's. But the 8090's are not really a great tire. They are the worse summer only tire that Dunlop make. They have 8000's and 9000's and Direzza's which have better grip. (despite the Direzza has a 300 tread wear rating compared to the 8090) The 8090 code means these tires are really only available as OEM equipment when you buy your car new. I don't think you can find these tires for sale at any tire location, only perhaps from the dealer. Mazda buy these 8090's in bulk for a great deal when they are manufacturing the cars. Dunlop do not put the best they have into the tires that are bought in bulk at a great price. They do the same crap with motorcycle tires.

Regardless of the tire you have, you will notice the car drift around more as you wear the tire tread off. I have the Dunlop Direzza's which I have drifted, done track events, put on lots of street miles, everything. They barely even warm up to the point where grip increases after 1 lap. Now they are totally bald... and I mean there are no signs that tread was ever on those tires... it's awesome for driving sideways as it slides everywhere, but terrible for safety.... and in the rain you might kill yourself. But you really don't start to notice this extra drift effect until you reach the wear bars, and it really increases with about 1mm of tread left.

Only R-compound tires will heat cycle and you will really notice grip levels to increase after 1-3 laps. Even Toyo RA-1's at a tread wear of 100 just begin to heat cycle. In fact, most club racers will tell you that even RA-1's are immune to heat cycling, although they must to some very small degree that even racers can't tell on the time sheets. (perhaps it's also becuase RA-1's have the best grip from 20-40% tread left as most rain grooves wear off) RA-1's you can really feel coming into grip after 2-3 laps, whereas the street tires I've used feel virtually the same after the 3rd corner. Most tires that heat cycle have tread wear ratings of 40-60.

You are more likely noticing cooler ambient fall temperatures affecting the grip level of the tires. Or perhaps you are more agressive with the car becuase you just got lots of practice on the twisties and you are going into corners a little faster and getting on the gas a little earlier, with just some more giddy up and go.

iridearocket

...if you are now driving around in cool temperatures, you will notice less grip than when you were at the TAIL. Although I said the tires will not really warm up.... that applies more to hot summer days. Continuous cornering vs street driving in cool weather will allow you to detect a difference in grip. Continuous cornering vs driving on a 95 degree summer day will not allow you to detect much difference.

Umbra

It may be the cold temp. There are a few tires that you need to store in the winter so they don't get too cold as it permenantly affects the compond. I doubt that the dunlops are like that though.

Shinka13

I said "heat cycled" and it was thought that I was talking about getting a stock tire warmed up for better grip. I know that's not possible....but I'm wondering if it's possible to overheat a stock tire and make the compound stiffer. I guess that's the way I should have phrased it. I know it's not the colder temps....like I said, it started happening before I even left North Carolina. I really don't think it's because I drive the car any different now....I've always driven hard.

Aseras

if the tires are worn, you will have less grip. when it gets cold or wet your actual tire as opposed to the tread gets closer to the road and has less surface area so you loose traction and it get's colder faster.

check your air pressure.

Shinka13

Pressure is good, I now have about 4-5/32nds. When I went to the Dragon, I was down to 5-5 1/2 32nds. Not that much of a difference.

ZoomZoomH

iTrader: (1)

actually that little bit of wear just may be enought to affect its traction

iridearocket

Shinka,
I hear ya, but I've destroyed some street tires on the track, which will have warmed them up well beyond their normal operating temperature and beyond what can be done at the Dragon. I've even had them well over operating temperature, several times per day for ~30 minutes at a time. You could not trash tires any worse. Sometimes I drift them and burn them up, other times I just try to put in fast laps. I've not noticed any such tire grip change after a thrashing. I also know a few guys wrecking their stock 8090's on the track and they work just fine, session after session. If there is any change after going to the dragon, it would have to be negligible.

skillmaker

Just one more question - How old are your tires?

Tires do tend to dry out, the compound changes, gets old, loses traction, simply based on oxidation and age.

Also, if you use your tires for daily driver, then you will also find that cycling through wet/dry/seasonal temperature changes/etc will also tend to 'dry out' the compound and shorten the life cycle. When the rubber compound changes, it will reduce traction and control. May also increase noise due to less deflection and give over minor road abrasion.

Rule of thumb that I have always used for performance cars and performance tires: If the tires are older than 3 years, regardless of treadwear, it's likely time for new tires.

No offense intended to previous respondents, but we are not talking about a truck tire here. I believe that track days, Dragon days, and hard daily driver usage will definitely AGE a tire faster. Running a tire at the track or at the dragon will likely heat it up beyond it's intended temperature range. When the tire gets aged due to many factors, the RX will let you know!

Shinka13

Car was born in Dec '04, so they're not that old. The whole age/drying out issue is why I'm not jumping all over a set of 245/40-18 Kumho 712's for $80 a piece. Those tires where made in '04 and have sat on a tire rack in the same position, being taken inside and outside every night/day since received for just over a year. They've been rained on, snowed on....everything that a normal tire goes through, but the thing that I'm concerned about, is the fact they've had they bright summer sun and UV rays beating on only half of them every day.

Thanks to everyone that's replied so far.