No prob, that's why we are here.

A t-bar mounts at the pivot point, so it is 1:1 spring rate to wheel rate. A coil over mounts somewhere else out on the control arm, so its spring rate is reduce by the motion ratio difference between the overall length and the spring mounting length. EG: On a stock 2nd gen Camaro, this ratio is almost 50%, so a 500# spring rate produces 250# wheel rate. An aftermarket coil over will most likely mount the coil somewhere else on the control arm which will either reduce or retain a % of spring rate.

Wheel rates are what you need to compare apples to apples with the force applied at the wheels compared to another car. Eliminates all the variables in spring size and geometry.