Too big on a front bar will make the car push (go straight when u want it to turn). Usually, a certain car had a 6 cly. engine and small bar, a small block v-8 and a middle sized bar and a big block with a large bar.

Try to get the one that best matches your combo. (A good starting place as any) I always prefered a LARGE front bar with a small rear bar to balance it out, but it is extra work over the correct front alone.

Car balance can be determined by driving up to 30 MPH or so in a vacant area, then turning sharply to observe the handling.

1. Car turns sharply, but front rolls a lot= needs a larger front bar.

2. Car tires screech, body rolls some and car goes kinda straight turning a little = too big a front bar. change to smaller or mount a small rear bar .

3. Car turns ok, body sways a little, but better overall than no bar = perfect.

These are generalizations.

The wheel rate is determined by road conditions. Flat surfaces prefer soft springs and stiff bars. Banked surfaces like stiff springs and light bars. But the wheel rate totals stay the same.