Does driver weight affect tire pressures?

So, I’ve noticed something interesting this year with one of my teammates and myself. Going into most sessions, it seems like I always prefer to start my tire pressures about 2 psi higher than he does. If I go with the tire pressures Josh likes, I usually end up sliding around a lot for the first 2 or 3 laps before they come in.

The only difference between us and our kart setups is that Josh is about 4 inches shorter than me but weighs 25 pounds heavier, with a good bit more upper body weight. This means he has less weight mounted on his seat and more up above the rim of the seat.

He’ll also sometimes say at the end of a race or session that his kart got greasy at the last couple laps, whereas I rarely ever have this problem even at 2 psi higher. I wouldn’t say I’m any better of a driver than Josh, last time we went to a practice session together we were 2 thousandths of a second apart from each other in lap times, and I would argue he’s probably even smoother on his inputs than I am, so I can’t think of any other reason the tires would be behaving so much differently between the two of us, other than our different sizes and weight mounted on the seat. Most of my weight is also mounted at the bottom of my seat, under the legs or right at the hip, and a 4 pound weight at the floor tray.

I personally think that driver weight, and balance affects the tire pressures that you use.

Also, each driver’s driving style can affect what pressures you use, depending on how you like the pressures coming in/how well you can deal with an uncomfortable kart when pressure are not where you like.

Since the overall kart weight is the same, I think it’s less about the driver’s actual weight and more about how that weight is being used.

I’ll tell you right now, the reason Josh runs less pressure than you is because he drivers the sh*t out of the go-kart. He uses his tall upper body more than 95% of the drivers out there and really aggressively works the go-kart.

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