I'm not patient enough to read what everyone else has stated above, but if you haven't figured it out already... radials can require a very different chassis setup than bias-plies.

Things I found critical getting my car to launch straight and stay hooked up:
1. Needed to lower my front ride height and cut down my upper control arm bumpers to get the 5+" free travel from static height; before that it would hook, then top out the front suspension and unload the rear tires
2. Only required about 1/3 turn additional pre-load on the passenger side to get it to go straight
3. My shocks are the OLD Ranchos that have 5 damping adjustments and mine are on 4 (one from stiffest)... and I'll probably need to upgrade to a decent DA in the future
4. Tire pressure... even 1/2 psi too low and my 275/60R15s would squish the sidewalls too much off the line; on skinny 8" rims they needed 17.5 psi to work OK and I've yet to try 'em out on the new 10" rims
5. Don't stage your car at such a high RPM that you're torqueing up the suspension; bias-plies can be a crutch for that, but radials need the pitch rotation to stick
6. Marginal tracks and radials don't get along well