Q: “The question I have is about heat treating to break in new tires and improve tire longevity. I usually heat cycle a set of tires for 20 minutes on a single session, then take the tires off and let them sit for 24 hours. I then put them back on for the remainder of the 2-3 day event. I run a set of tires for about half a season, ~4 events. Is there a better way of getting the tires ready for a season, and is there a normal life of tires that would indicate a replacement point? Could I run tires for a full season without suffering hardening and loss of grip?”
A: I am no expert on trying to stretch the life of tires, so my input here is very limited. My big question is whether initially running your new tires for 20 minutes is too long? When teams I’ve driven for wanted to prep a set of tires for a long stint(s) in endurance races, we’d only run them for a few laps – just long enough to scrub the mold release off and scuff the surface of the tire, but not anywhere near getting them to their peak temps – and then put them away for 24 hours or so, like you’re doing. I don’t have specific experience with those Hoosiers, so what you’re doing might be perfect. But that 20 minutes might be too long, too. Unfortunately, the only way to know whether making the initial run-in shorter is to try it. It is important, in my experience, to initially bring the tires up to temp gently – so, not going really hard and fast from the first lap. Instead, bring them up to temp gradually, without any big moments of sliding them.
I’d recommend asking the tire manufacturer for this information, but be prepared to not get much back from them. Sometimes they don’t even know what’s best for someone wanting to extend the life of their tires (they’d rather you bought more new ones!). Still, it’s worth asking, as I’ve also gotten really good info from some of them.
As for how long they will last, I don’t know. Again, I’ve not used those tires. But it’s rare that a tire does not gradually – and sometimes not so gradually – lose grip over time. Could you run them for a full season? My gut says they’re going to lose grip after some amount of time. When? You have to learn from experience. Obviously, it also depends on what tracks you’re running on (Laguna is easier on tires than Willow Springs, for example), and even the ambient temperature at each event.
For sure, there is no “normal life” for tires, because every type is different. Even your driving style will make a big difference. If you’re really leaning on the tires and using every bit of grip, on every lap, they’re not going to last as long as if you’re easier on them. Of course, if you’re easier on them, you’re also likely to be slower, so you need to decide which is more important.
One thing I would recommend is keeping a notebook (or on your phone) with a “grip rating” after every session, along with things like weather and track conditions. For example, if during your first time on track, after the 24-hour curing time, you have maximum grip, then rate that a “10.” With each following session, ask yourself what the grip level was like. You may find that the grip has a drop on your second session/event (i.e., to a “9”), and then stay that way for 3 or 4 sessions/events, and then another drop (“8”). If you’re okay with the “8” grip level, you can continue until you notice another drop in grip level (“7”) – maybe that’s when you decide to put new tires on? Over time, you’ll get better at predicting the life of your tires, and that’ll help you in your planning in the future.
I’m sure you know to store your tires in a cool, dark place in between events, as that will help keep them consistent for a longer period of time.
When I was running FC and FF I went by both feel and heat cycles, marking each cycle on the sidewall with a yellow or white tire marker. I heated the new tires slowly and cooled them down on track slowly as well. There was a noticeable fall off in grip at about six cycles depending upon track temperature, surface and so on. Being on a budget I tried to stretch the tire life to three SCCA regionals or two Nationals. Tires were harder back in the day though so YYMV. I only used Goodyear slicks back then. Hoosier was just beginning to supply tires for small bore formula cars. Generally I went through two to three sets a season. The price for a set of FF slicks was about $400.00. Those days are long gone though.
So, yes I was able to run my Hoosiers for a full season with no loss of grip, I’d actually come home with more rubber than I left with. Yes the first heat cycle worked as you stated, then at the end of weekends, and sometimes during the weekend, I would use the heat gun with scrapper I made to clean the pickup rubber off the tires and then I treated my tires with Formula V which put back the softness that heatcycling took out. I buddy with a pyromiter measured his new stickers and mine one weekend at Sebring and actually found mine were softer than his and I had multiple weekends on mine. So yes, cheap bastards I am, I was able to actually win two regional championships in a row with my used tires.
From my perspective, tires vary a lot in grip, longevity, and heat tolerance. They are contact patch tools so choose the best tool for your particular purpose and then use the mfg. recommended break-in heat cycle to get the most from them. For most track tires I prefer to warm them up to temp slowly, get in 2 tidy hot laps with no sliding, 2 cool down laps, and then store them for 24 hours or more. This seems to provide the most consistent grip and the best longevity within a tire class.
A few common choices:
1. Hoosier R7- A brilliant 40 treadwear tire for golden laps over a few heat cycles, then they fall off quickly. For Quali laps, Sprint racing, or Time Trials these are great but often only for 1 golden day. After 4-5 HC they have noticeably less grip and after 10 HC they begin to feel like hockey pucks with lap times falling off several seconds.
2. Nitto NT01- A 100 treadwear tire for DE, TT, and endurance racing. Not as quick as the R7 but they really stay in the game without significant loss of grip for up to 40 HC or 8 track days. Very consistent from stickers to cords.
3. Falken RT 660- A 200 TW tire suitable for Autocross, DE, TT, and Endurance racing. Similar performance to the Nitto with a more noticeable but gradual fall off of grip over time. Also good for 40 HC and a top choice for Lemons endurance racing as a track capable street tire.
These are just a few popular choices in 3 different tire classes, and there are many others. Choose your tire class, break them in per mfg recommendations, and keep data on their grip and longevity to find what works best for you.