Ramp slope for parking

[sahu.mgse]

Dear Members;

My car parking level is at 18 inch height from road level. what is length (minimum) required for Ramp for comfortable car movement between road to parking area and vice versa using ramp.

I am also looking detail about chappading stone with respect to thickness (for ramp), price and type. Any dealer (including contact no.) in and around murugeshpalya/Old airport road ?

Looking for reply from experts.

regards

Sahu