If you are suffering from the harsh ride, talk to @ CRS Performance and consider a suspension upgrade to KONI. I do not suggest lowering tyre pressures below manufacturers suggestions that could be illegal. However the larger tyres more voluminous tyres have lower pressures for instance mine are now F 35psi, R 34psi unladen but are oversize BFG KO AT 255/55R18. Pressures originally where in the 40's i seem to recall 44/41psi. I use a tyre comparison site to compute the new pressures. Most people when shifting to different tyres use the same pressures as old when going up in size but they could be over inflated. More expensive again is going air suspension and not for low-down street cred but some feel it is a better more comfortable ride ride. Seating is another important thing , firstly make sure that your posture is good there may be Physio type video around showing how to sit in a car and hold the steering wheel. Certainly a Physiotherapist could advise. Another thing is to have the best seats preferably with multiple adjustments. Depending on what the trouble with your back is but many men suffer low back pain and the simplest thing to do is to role up a towel and place it in the small of the back to support the natural lordosis or curvature in the small of the back. Most people, especially men sit with there arms too strait bad for control but also puts the body in an unnatural posture.
If some one is suffering back pain there is a lot to do for ones self but the best thing is to take advice to have it diagnosed and often or not certain exercises can help Physiotherapists are the best for advice.
