I usually run 315/60 M/T Drag Radials but I went to T&T at a marginal hooking track. I have a set of old 29.5/10.5W slicks on a 14 in. rim and I put them on my D50 to try. It hooked every pass but It would pull the front wheels about 3 ft. off the ground and head straight to the right every time.Most of the time I had to let completely off the throttle. It has never done that with the Drag Radials. I was wondering if one of the tires is bigger around than the other one or what do you think what the problem could be. What is the best way to measure the circumference?

I use a seamstress tape measure to measure mine.

Next time swap sides with the slicks and see if the
problem moves with them

Well all I had to measure them was a regular tape measure and it showed the left was a 1/4 in smaller than the right. I know that was probably not very accurate and showed the opposite of what could be the problem so I just swapped sides and I will just see what happens. I will also carry my Drag Radials and swap them out if it is still going to the right.
I am running caltrac bars and they say if it is going to the right to put more preload on the right. I tried that yesterday and it did not help at all, maybe worse.

Heck I've checked them with a string.

Slight air pressure differences can make them the same diameter but may also affect how well they hook.

buy your self an[8'x 1/8 "] tape to measure the tires . circle track tricks.... inflate the smaller tire to 70-80 lbs and let it stretch in the sun. it will be larger than you need for a little while but will stabilize to a smaller size. you can measure the tire with the extra air press. and learn what amount of extra time and pressures it takes for your type of tire. this works best with bias ply tires, however ,it will work to some degree on all tires. also , you can add air to one tire and subtract from the other to adjust the steering from the rear tires

There is no way that I would put 70 to 80 pounds in a slick!!! I wouldn't go past 35 pounds, slicks are pretty thin, and not designed for that much pressure... Circle track tires are a lot stiffer than a slick...

At 40 lbs it will grow 1/2 of an inch over night an 1/2 wider. we do this all of the time.

Put a small blob of enamel paint on the center of the tread and roll the tire...measure between the paint dots.