I am running 245/35/20 and 275/30/20 on my 2006 530i with OEM sport suspension. Usually the car rides very cushioned and smooth. Today when I drive my car, I feel like my left front tire (or tires) is running over every little bumps on the road. Could the sudden bumpy ride be the result of low tire pressure due to cold weather??? Please feel free to chime in.

 

Check tire pressure and your thrust arm bushings. OEM sport suspension has always been known for its rough ride, but you also have 20's which doesn't help and if you've never replaced the bushings that definitely doesn't help either.... car is 6 yrs old and bushings last for 3-4 yrs.

 

Thank you, sir!

 

BTW, low tire pressure would have the opposite effect. The low tire pressure will create a very soft dangerous ride, but only on the corner where the low pressure is.,

 

+1. Over inflated tires would feel more bumpy.

 

Have you checked tire pressure all around? 35 PSI front and 38 rear. Cold tire pressure done first thing in the morning is most accurate.

BTW, are you running on new tires or old?

 

Thanks guys for the responses. It turned out that my front, driver's side tire had very low pressure. After inflated the front at 40 and the back at 45 psi, the ride is back to normal again. I no longer feel the lumpy, abnormal, uneven ride on my front, left tire. I guess I felt the roughness of the road more because I was riding on more metal versus rubber.

Have a great weekend!

 

40 and 45 psi sounds way too high. Check your manual or door frame for the correct pressure for your tire size. Maybe that is required for 20", but it still seems high. With your large rims and high pressure your ride must be very harsh.
Glad you solved your problem.

 

Agreed. 40-45psi seems too high. When on the free way and under direct sun, they may go up to 50 psi especially during our warm winter here in SoCal. I would think that it would warrant safety concerns.

 

there is nothingggggggg you can do to solve that problem. My 550i sport suspension rides rough with the stock 18s so i can just imagine the 20s. The only way you can get a little ease is finding the perfect tyre pressure. I run 32psi in my rear (275/35/18) and 30psi in the front (245/40/18). If i run more than that the car will feel like s#it.