No doubt this is a dumb question... But how do you know if you have the correct air pressure in your slicks. I've got 28x10 Hoosier now. I've been running 14.5 psi. My wife came to the track and took some pretty good pictures last night, seems like they might be rolling up a bit to much on launch. I wish I could describe it, or better yet post a picture.... But I can't. Anyway if y'all can help I'd appreciate it. I made it to six cars last night and four the weekend before. I'd like to be able to seal the deal before the end of season. Btw. Car runs 7.20 1/8 mile. 1.58 60ft. 68 dart. Weight unknown.

Jeff.

I was told years ago by one of the race tire reps at one of the NHRA National events to lightly run my finger tips across the tire surface on bias ply slicks and feel for roughness, if it is consistently rough(same texture) from the outer edge to the inner edge your good
If it is smooth on the outer edges and rough in the center it is over inflated , if it is rough on the outer edges and then is smooth and rough again and smooth near the inner edge it is probably under inflated
I use to pump my nine inch stocker tires up a 1/2 lb. at a time until it started to spin and watching the sixty foot times and then back in down 1/2 lb. I was up to 17 lbs. on my last set of Firestone 9x30 on 10 inch wide rims back in 1988, 1.41 60 ft. times on a 1963 B/SA Belevedere 415 HP M.W.

Yep. What Cab said. Also, do you run tubes? I do and my setup likes more air than without. Weight of car is also big factor of how much pressure. Try to weigh it next track day

As described above...but basically, as much air as possible while maintaining a full-width footprint. Too much "wrinkle" isn't good for sidewall life and the "wrinkle" can extend to the tread. But the wider the rim, the more air you can usually run. Stock class cars that are limited to 9" slicks usually run 10" rims. I run around 20-21 in Hoosier radial slicks, weighing 3,540+, footbraking, usually around 1.49 - 1.50 with 7-teens.
Radial slicks are a bit faster and take a bit more air than bias ply slicks, but not as consistent on marginal tracks.

Shocks/suspension could be hitting the rear a bit too hard as well. But if you're consistent & going rounds, that can't be too far off.

It would only be a "rough" indicator because it probably wouldn't be hooking and transferring weight like on a prepped track, but launching on clean pavement, set up like at the track, can help show your footprint and possibly go up a bit with pressure from there, if needed.

I think you are pretty close. You can go up in 1/2 lb increments until you slow down, as said earlier, then drop back down 1/2 lb. My car is light, with a big tire. I start slightly high on pressure, and work my way down until the car gets a little sloppy on the top end, then go back up 1/2 lb.

Thanks much folks.

I don't run tubes.

We unfortunately don't have scales at the track. I've been thinking about taking it to the truck stop to get a rough idea what it weighs. I don't know of any other scales around here.

It's a foot break car on super stock springs.

My '65 Valiant weighed 2960#. I ran M & H 10" slicks (with tubes and rim screws) at only 10 pounds. Equipped with a four-speed, 4.56 sure-grip, super stock springs and shocks. I know, not your set-up, but good to know stuff. I never noticed any top-end instability, trap speed was 108 MPH.

I wouldn't, and don't, trust commercial truck scales for lightweight things like our cars I used a local Oregon state truck scales once on my old street Duster, it showed it 220 lbs. lighter than the certified scales at the track showed
Do you know any roundy round racers that have a set of four corner scales for their race cars? If so see if they will demonstrate them to you on how well they work your car