Put a baseball bat at about 9 oclock on a front tire, leaning the bat at about a 45 degree angle.
Have someone push the car forward while continuing to hold the bat against the tire.
Eventually, the bat will hit the fender lip.
Keep rolling the car forward as the bat "nudges" the fender lip up.
By the time you're at about 3 oclock, the bat will have moved away freom the fender.
Repeat this, holding the bat at a slightly different angle so it "nudges" more of the fender.....keep repeating until you get the required clearance (not always possible, depending on tires/wheels).
This really doesn't work on the square-type fenders on a box-Spridget. It can work OK on the more rounded front fenders though. I've used a 2X4 to do this too.
To get good clearance on square fenders usually involves real body work. By the way, there is precious little clearance between the leaf springs and "inside" of the tire, so sometimes you need wheel spacers, making the fender clearance even worse. You can see why many folks "convert" to RWA (1972-73) round-style Spridget fenders (as I have done, as seen in the picture below).