I was looking to see it you had responded to your original thread about this. Defender110 has suggested possible problems to look for but your front struts could be sticking / worn. If you changed your spheres believing you were having a harsh ride on the old ones and you still have a harsh ride now, it could well be the struts, especially since you were
concentrating on the front end in your last thread. You have not given much info about why you did the swap. Is your LHM fluid / filter / reservoir clean. Also, is your seat still in good condition with good padding?
55's will not perform correctly anyway if any of the aforementioned is at fault (not so much the seat though). Plus, I do not think 55's will be good on the rear of your car, it will dive at the rear even driven sedately.
Tyres are checked so not those at least.
