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View Full Version : useful life of street/R compound tire


tnord
01-30-2003, 08:31 PM
from another thread:

the fact of the matter is, a tire's useful life is about a year. the sun, temperature changes (heat cycles), and just pure age deteriorate a tires ability to grip. even though you may still have enough tread depth, the tire just isn't what it used to be. i change my tires pretty much ever summer (of course i trade cars about every summer as well).

the "life" of a tire may be even shorter than that.........i dunno. all i know is my tires sure as **** don't grip like they used to.

which gives me an idea.......

that idea was to ask you smart guys how long tires last. i'm not so much concerned with mileage, but how many heat cycles, or how long (as in months), a sticky street tire will last.

what about R compounds? do heat cycles effect them as much? what about the sun etc.......

the book i have didn't give anything close to an answer, or rule of thumb.

*cue mike gerst

AceInHole
01-31-2003, 12:36 AM
From The Tire Rack (http://www.tirerack.com/tires/tiretech/competition/heatcycletech.htm)

The first time a competition tire is used is the most important. During that run, its tread compound is stretched, some of the weaker bonds between the rubber molecules will be broken (which generates some of the heat). If the tires are initially run too hard or too long, some of the stronger bonds will also be broken which will reduces the tire's grip and wear qualities. Running new tires through an easy heat cycle first, and allowing them to relax allows the rubber bonds to relink in a more uniform manner than they were originally manufactured. It actually makes them more consistent in strength and more resistant to loosing their strength the next time they are used. An important heat cycling step is that after being brought up to temperature, the tires require a minimum of 24 to 48 hours to relax and reform the bonds between their rubber molecules.


Speculation time:
So... if that applies to the tires beyond the first runs, as you heat cycle the tire, eventually the stronger molecule bonds will break and your tire will not grip as well as it did before. For R compound or competition tires, it's fairly obvious that they would be more succeptible to the unwanted affects of heat cycling, and hard track days with intense heat cycles would have the greatest impact (wearing the tire physically both by stresses from intense force and heat). How long the tire lasts would most likely depend on how strong the molecule bonds are..... which depends on how soft the tire is.... which we all know is very soft for R/ competition tires.

Yeah... I know I'm supposed to be sleeping, but guess what... I cleaned off more of the head. Can't go to class tomorrow without a clean head if you know what I mean.

240racer
01-31-2003, 01:46 AM
In general DOT tires are going to be harder then full race tires, for a couple reasons. This makes them less heat sensitive. It's not just that they are harder, the compound is made differently to have more consistant performance regardless or heat and wear. Wearas race tires are made for a very specific temp and load. If it's too hot out, or the load is too high, or they do not get the cooling necessary (closed wheel cars) then they blister. And if it's cold out, they have much much less traction. I think that R coumpound tires (having never driven them) are more stable, they react to heat, in the sense that they like it and have more traction, but I think it would be extremly hard to blister them. I also think that they may have similar grip when cold (well out of the range that they are made for) to race tires. Also, some of you may noticed that snow tires especially the blizzaks have a very soft compound, however, it won't heat up and become sticky like a race tire, in fact it has much less traction then the hardest touring tire on dry pavement, no matter what the temp is. It's more like foam then rubber, any chemical engineers herer that want to explain the difference? I did see a kid at the drag strip with blizzaks on the front of his cavelier or something. I think there is a material diference between race tires and street tires that makes race tires have a higher peak, but more sensitivity.

As far as heat cycles go, I would not be surprised that the thing about race tires that makes them sticky and peaky is also what makes them greatly affected by heat cycles. I don't think that R compound tires are going to be affected by that as much, but they still will be. Going along with what ace said, maybe the R compound tires have stronger bonds that allow them to wear longer and not break as soon, so technically you have to push them more to cycle them. However, with a regular street medium performance tire, the compound is harder, it has more carbon black in it (the stuff that makes it durable) and has stronger bonds that don't allow it to form to the pavement and therefore have less grip. I think it's just a nice transistion in compound from hard all-season tires to performance tires to R-compound tire to full race slicks. Each one has progressivly more oil and less carbon black and whatever else that makes it stickier and more temp sensitive. THe biggest jump is still between R and race slicks.
Has anybody noticed a difference in grip between cold all season tires and warm or even hot all season tires, I don't think I have. I think that's because their bonds are so strong and they have very little ooil content they just don't get affected by heat like that.
Also, tires loose the oil into the atmosphere whether they are being run or not, so I would say the older the tire the worse te grip no matter what tire. However, it affects race tires more since they have more oil and grip to loose and they probably loose it faster too.

HippoSleek
01-31-2003, 07:14 AM
More info please... what type of R compound are we talking here? Do you want to run Hoosiers or RA1's? The RA1's have more heat cycles in them at the expense of ultimate grip. I don't think you'll find a much longer lasting sticky than the RA1.

Now, there are plenty of SM guys running a full season (10-12 events) on two sets of RA1's (and a few who do it on one :o ). So say you get two practice sessions, a warm up, and a race per event. That would make roughly 4 cycles per event. Multiply by number of events.

As for sticky street tires, I can't tell you what you'll see for wear, but I can tell you that heat cycles aren't an issue. I wouldn't be too worried about the sun either unless you lived in AZ or the deserts in CA. Honestly, I've never known anyone who's thrown out a street tire b/c it wasn't sticky -- it's always b/c its worn out. If I were to drive my car at its normal pace, I wouldn't get a year out of my street tires (and I put about 6,000 mi on the car this year). But that's not b/c they are "heat cycled" out but b/c the shoulders look like hell and they're generally getting low on tread.

HippoSleek
01-31-2003, 07:18 AM
Originally posted by 240racer
Has anybody noticed a difference in grip between cold all season tires and warm or even hot all season tires, I don't think I have. I think that's because their bonds are so strong and they have very little ooil content they just don't get affected by heat like that.

I don't know enough about the chemistry of tires to respond to much of Adam's point (I think I generally disagree though - if I read it right). But I will say that, having done a track day on all seasons in Sept., I noticed a HUGE difference b/c hot and cold. A hot all season tire is like driving on marbles - the car was VERY loose and the tail would inch around with any application of the throttle. Great for drifting, I'm sure, but scary at an HPDE.

tnord
01-31-2003, 10:19 AM
heat cycles may not be an issue with street tires, but i believe that age is. maybe it's in my head........but i don't think my tires grip like they used to, and they're about 1.5 years old now. now what about driving in the cold........i've heard that using what are supposed to be sticky tires in the "cold" also ruins them. so how cold is cold? i've used them when it's like 30 degrees outside, but never in the snow.

i was more thinking of RA1's or V700's.

HippoSleek
01-31-2003, 11:38 AM
I don't think that age is so much an issue as is storage and wear. A guy w/ a cool old 2002 was running new a008's - and they were sticky hell. Now, that tire hasn't been made in probably 3 years? But w/ proper storage, it wasn't an issue.

Exposure - including hot/cold/hot/cold, rain, sunlight, etc. combined with use does have an effect. I'd wager the stickier the compound the greater the effect. Everyone I know who stores R compounds does so indoors so I think that says something.

To me, the missing peice for less feel is more likely wear. If your tires are 1.5 years old, they are likely more than a bit worn. Also, driving any type of performance tire in cold yields poor performance. I keep saying that on a sub-35 degree day, I can easily spin my RE71's into third w/ a bone stock KA. There is much less grip with any performance tire when it is cold.

Now, RA1's or V700's are among the longest lasting stickies. Two questions: 1) do you need that much grip on the streets; 2) are you really willing to substitute reduced life, increased danger, higher cost, etc. for the minimal work of changing tires at the track?

I think my next car will have a tire trailer.

tnord
01-31-2003, 11:54 AM
i think we've got some miscommunication here mark-

i wasn't talking about a loss of grip when it's cold....i know that happens. but more referring to loss of MAXIMUM grip. of course, i could be just overdriving the car as i have a tendency to do, so it feels worse.

the RA1's or V700's wouldn't be for street use silly :p , i would get another set of wheels and have them for dedicated track use. i'm not even really giving that much thought to purchasing any, it was just a question that popped into my head.

ps - i'm jealous of you and your RE71's, i had them on my Z32 and ripped through em in about 7k miles, but damn were they nice.

HippoSleek
01-31-2003, 01:14 PM
Okay, now it makes a lot more sense... I was trying to think of the most polite way to say: "Hey jacka$$, race rubber is for track use, street rubber is for streets. Yeah, race rubber deteriorates in cold, etc." Much easier now :D

The reason I brought up my car in the cold is b/c I don't think there is any way you can compare a performance tire's performance in January. If you meant at the end of the summer, then you might be overdriving the tires or they might just be overly worn.

Most people around here who run HPDEs on R compounds do it on RA1's, A032R's, or V700's. The RA1's and A032R's have similar wear, V700's get too many cycles entirely too soon. In either case, get them shaved to avoid chunking and you will see a decent life for HPDE use. With the RA1 and the V700, ultimate grip doesn't fall off as severly as w/ many other compounds - basically, you can drive a set that is overcycled w/ minimal dangers. I still don't think you'll see one set that will last a between summers - but if so, storage will keep them fresh. When I get the Miata (likely soon), I will be getting some shaved RA1's, even before it goes to spec. I might drive this whole season w/ a Miata w/o putting it to Spec just b/c I've got to take a few grown up steps like buy a place, get engaged, and think about marriage. As much as I hate to think like an adult, I really need to for the next two years :(

Oh yeah - personally, I would never run race rubber w/o a 4 point bar. I know you have classing issues, but I wouldn't feel right posting this w/o that dislcaimer.

tnord
01-31-2003, 01:25 PM
i'm most likely overdriving the tires........as with my experience i have become far more comfortable driving like a quasi-mainiac on the track........which is to say; a fair amount of yaw on certain corners.........which is to say i'm probably near the limit of the chassis and suspension, but past that of the tires.

i do store the tires inside, in my bedroom in fact :) and i will be getting new ones before the season starts, i just don't know what. or even if i'll need to if i get a new car (considering 95 M3/early 90's NSX now.......but that'll probably change in a week).

i kinda know the think like an adult thing. with an upcoming job, and no real expenses (will be living with parents for 1yr), i could faily easily afford a pretty badass car. but at the same time i'd feel like an idiot owning an NSX and living with my parents. not to mention that the money spent could go to buying a house. (housing market will collapse soon enough, but that's another story altogether). on the other hand.........live while you can right?

MovinUp-1
02-01-2003, 08:00 AM
I'd like to clear up a couple of misconceptions here. Rain does not affect the chemical structure of the tire. Storage in cold temperatures does not affect the chemical makeup of the tire as long as it is not below 30 degrees. Sunlight can start to break down the tire structure. The only thing that really affects the available grip of the tire is the number of heat cycles (as long as the tire isn't dry rotted). I've heard of people that stored tires in their attics thinking they were out of the sunlight so they were fine. Well here in the south temps in an attic can reach well over 120 degrees. That close to the operating temp of these tires. So this guy got to heat cycle his tires for a few months. they came out of the attic hard as stones.

tnord
02-01-2003, 11:10 AM
what's so special about 30 degrees? why is that the magic number? is that for all tires?

MovinUp-1
02-01-2003, 12:16 PM
I guess that is the temperature where a chemical change starts to occur in the tire, but i am guessing here. I have been told that temp by my tire supplier (I run Hoosier slicks) and my friends that run Hoosier Rs have been told the same thing

HippoSleek
02-01-2003, 12:51 PM
Yeah - I've heard "freezing" is when it gets bad.

And oops on the mention of rain. I was just thinking about the elements and got carried away :embarassed:

Another factor that is separate from sunlight, but nearly as important is humitity. When I lived in AZ, most tires (even all seasons) were dead in 1-2 years b/c of the combo of heat, sun, and dry air.

tnord
02-01-2003, 05:23 PM
Originally posted by MovinUp-1
I guess that is the temperature where a chemical change starts to occur in the tire, but i am guessing here. I have been told that temp by my tire supplier (I run Hoosier slicks) and my friends that run Hoosier Rs have been told the same thing

good enough for me.........i was just making sure you didn't just pull that number out of your a$$.