If you feel like simply having to loosen the car, there are no guidelines...just guess what you can drive and give it a try.



As far as fuel load is concerned, there's a very simple rule of thumb:
Add 1 click of right side track bar (you can't adjust the left side in the pits) for each missing gallon.
Iirc, that works on any track except Marty, the RCs and SS.

Examples:

1. You stop for tires only with 14 gallons left in the tank. 22-14 = 8 gallons => add 8 clicks = 2.00 inches of track bar

2. You stop for tires and half a can (=6 gallons) of fuel with only 3 gallons left.
22-9 = 13 gallons => add 13 clicks = 3.25 inches of track bar