Tire pressure on wet track

I have a coyote widetrack. I honestly don’t know much about how it’s set up right now since I bought it used and am trying to establish a baseline with where it’s at to make adjustments from there. Besides that, I’m so new to this and figuring it all out on my own.
I was reading through some tire pressure threads about temp, but didn’t come across anything about a wet track. Generally speaking, do you adjust your tire pressure much for a wet track?
I was out yesterday (only my second time on the track) and it was still wet from a lot of rain the night before. The temperature was also fairly low, slowing down the drying time. I was having a hell of a time getting around the corners without spinning out. Just as I was getting ready to leave, one of the other guys asked what tire pressure I was running, which was about 8psi, and he said he thought I could get more grip on the wet track if I was at a higher psi.
I know there are too many variables for anyone to tell me what my pressure should be, but do you usually adjust your tire pressure much for a wet track?
Or do you think it may have had more to do with my tire pressure for a cold track?

Are you using actual rain tires or driving on slicks?

Sorry, meant to mention that. I was using slicks. When I was talking to the owner of the track when I got there he said the track wasn’t wet enough to where they would use rain tires racing. I also didnt mention that it was just open practice day.

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Slicks is a bit of a crapshoot on a damp track. It’s sort of that unhappy medium, where it’s too damp for slicks and too dry for rains. Generally, if the track has a consistent sheen of moisture on it, we’re on rains for race conditions. You’ll shred the rain tire in those conditions, but it’s better than spinning or going off trying slicks.

If it was dry enough that it was truly slick tire conditions, you’re looking more at it from the perspective of how you would if it were a cold track. The goal in this case would be to pump the tires up with plenty of air so you can get heat in the tires. I’m not sure what compound you’re on, 8 psi is a pretty low number for almost any tire. On a very hot, sticky track with soft tires, we are down at 8 or so, but for most tire compounds that’s a pretty low number.

What tire is it?

I believe they’re Vega Reds. To be honest, I didn’t even think about tire pressure at all until that guy said something. I just bought the kart a couple weeks ago and took it to the track as-is.

Not too familiar with Vega Reds, but a quick Goog recommends 8.5 psi for cold pressures. If it’s damp out on a cold track, I wouldn’t be afraid to throw more air in and see what it does. 11, maybe 12 even.

Thank you. I’m trying to learn all of this on my own so I really appreciate the help from you, and everyone else on the forums.

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On a wet\damp track on slicks you’re going to set unusually\artificially high pressures. Essentially you’re trying to inflate the tire to reduce the size of the contact patch and therefore increase the pressure on the pavement from the tire…
Higher pressure on the contact patch\pavement makes it (more) possible for the tire to break the surface tension, “cut” through the water and reach the pavement.

The degree by which you “over inflate” the tire varies with how wet the track is and the average speed of the track. Higher average speed… more surface tension on the water to break, higher pressure

^ So that’s the theory…

In practice, the short answer is if it’s wet and you have slicks, slap in 40-50 PSI and SEND IT…. It’s not best practice, but it’s friggin fun. Don’t exceed 50PSI though, that’s bad.

James,
I had always assumed that the point of the higher pressure wasn’t to deform the tire (which makes sense) but rather to facilitate heating up the tire. My assumption was that a tire with more pressure somehow magically excites the oxygen molecules into greater frenzy. Since we are “water cooling” the tires, they can’t get hot at normal pressures?

Am I just plain wrong?

I guess the ultimate point is what works. Slicks are meant to be driven on a dry track. So all bets are off when it’s wet. The tire is deformed for sure with those higher pressures… but that’s what helps it break the surface tension of the water.

It’s a trade off. Slicks in the wet is not anything a chassis or tire is designed for, so you have to go outside of the norms IMO.

If it’s just damp and it’s going to stay that way then 40-50 is probably too high. Experiment and see what works for the conditions.

Or buy wets :joy:

Thanks. I guess I was asking am I incorrect In assuming that higher pressures = faster heating up of tire core?

No, you’re correct Dom. You’re reducing the contact patch and increasing the force on that smaller contact patch, so increasing the friction.

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Ah ok thanks. The smaller contact patch resulting in more “force” being applied to smaller area resulting in faster heating up makes sense to me.

That all makes a lot of sense. I ran it last weekend in a cold track (it was about 40 degrees outside that day) and saw a huge difference after pumping the tires up.

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