Spraying Tires for AutoX

johnson.ba

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Hi,
I just finished my 3rd AutoX with my mustang and this was my first one at a "big" event. I'm still an amateur(maybe 6-7 events run in total) and still learning the car and how to get it to do what I want. One big thing I noticed is that it seemed like everyone, except me was out of their car between run and spraying down their tires and some people were spraying radiators and intercoolers.

My car is stock(pirellis included) and I live in AZ the air and asphalt get HOT, should I bring my sprayer and spray my tires between run? I was running 36psi up front and 35 in the rear and over the course of 4 runs(36 car group) saw 2 psi increase in pressure. I was seeing scrubbing on my front tires that was just at the edge of the tread block before the sidewall, so I think my pressures were OK.

 

MrMagnetic

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Put your hand on the tread, is it too hot to touch? If it's too hot you should cool it down. The goal of spraying is to avoid overheating the tread, but they need some heat to be sticky. That's the advice an SCCA national winning driver gave me, then he loaned me his sprayer. My time improved after spraying my tires so I brought my own sprayer to the next event.
 

boardkat

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there is also a school of thought nationally that advocates NEVER spraying tires, to prevent premature heat cycling due to the rapid heating/cooling cycles that result (thereby preventing the natural cooling cycle where weak and broken bonds reform). fwiw, anytime i've autox'd a well-setup car with the proper amount of camber, and wide wheels/tires with the right compound (hoosier a7, kumho v710, bfg rival s, bridgestone re71r, etc), spraying wasn't necessary, even in 100deg temps with 2 drivers, my current steed among them.

all that said, on the stock pirellis - yeah, they're junk, some spraying will probably prevent chunking :)
 
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johnson.ba

johnson.ba

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I guess I'll bring my sprayer and try to be more proactive on tire pressure and I'll be sure to feel the tread between runs.
 

kz

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I guess I'll bring my sprayer and try to be more proactive on tire pressure and I'll be sure to feel the tread between runs.
I wouldn't worry about it. If anything - if it's very hot, I have trouble of getting enough heat in initially than overheat the tires...

I have done T&Ts and Evo advantage when I was running literally constantly -
maybe a minute between runs and did not overheat tires (RE-71Rs though).
At Grissom, on concrete somehow ended up with 9 tickets for T&T and not much time to use them :)
 


NightmareMoon

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If you feel like you're noticing reduced grip as the tires get hotter, and your tire pressures are <=37psi (and not 38+) and you verify they're too hot to touch (220+ degrees), then maybe consider spraying them..

Otherwise I wouldn't worry about the big time distraction of trying to spray tires between each run and would instead take that time for course visualization or review of things to change from your last run.

Spraying tires, checking times, messing with cameras, it all adds up to a bunch of stuff which increases the mental load and makes it harder to be mentally prepared when your run starts.
 

DocWalt

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I spray when they're too hot to hold your hand there. Otherwise... meh. I was definitely overspraying last year and noticed no real performance issues other than constantly having slightly too cool tires, lol. If you're overdriving the crap out of the car I could see needing to spray every run, but we're not in an AWD boost buggy that chews the front tires to shreds...
 

 
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