miniround

so ever since i got new tires and had them filled with nitrogen I've noticed too soft of a ride. took my car back to costco yesterday and had them put more nitrogen in the tires. Lexus recommends 30psi, but the mechanic said that usually michelins are put on our car and I have these bfgoodrich's that he said are a little more heavy-duty. so he checked all the psi's and to my disbelief they were all at 33. i said, thank youuuuuuuuuu, now blow them up so a man can drive this car. I'm now riding dirty at 39.5 psi all around. much better ride, I love not feeling like im driving a couch. only thing that sucks is the speed bumps in my neighborhood and at school. so i just go over them a little slower and feel them out with the hard tires haha

oh that brings up my next question. sometimes i go over these bumps a little fast and hear like a thump. I'm not bottoming out, right?! people told me its the wheel spinning in the air and then hitting the ground...i'm not popping a wheelie, but the wheel obviously doesnt ride the speed bump the whole way if im going faster......so someone tell me that what is actually happening..

greyBLITZ

iTrader: (2)

I doubt your wheel is spinning up in the air then coming back down. How much does a car weigh again? Going over a speed bump at 2mph isn't going to launch it; you wouldn't want to go much faster than that over speed bumps anyway. I think its the suspension, where it compresses the (whatever is inside the shocks) and that is what causes the sound.

miniround

ive done like 15... the bumps are about 2 feet wide, so its not just like a little curb in the road. I can hear the air or w/e in the shocks compressing, but I'm telling you, the car like slams down haha...uhhh

carguy07

Sounds like you are checking the pressure hot. It will always be several lbs higher than cold. If your tires are over inflated you will wear the middle out of them pretty fast. If there is even a chance that you are catching air on a speed bump then you are going way too fast. Go a normal speed and see if you hear a thud.

salimshah

There are rubber extension stops, inside the shock and compression stop on the body. You must be hitting those. [You are not supposed to hit them most of the time as something will give].

There is nothing magical about the recommended cold pressure. It is a suggested compromise based on ride comfort, tire wear, braking, rolling etc.

Do measure hot (after driving) pressure and make sure it is below the max molded on the tire to prevent blow outs.

One more thing to keep in mind, when you inflate on the high side is the belts have a tendency to separate quicker.

Salim

anulex

btw your car is bottoming out the shocks. my left front does it over moderat speed bumps a fomous bulge on I291 in CT where the bridge ends. i try and ignore it

Fern

Strut noise you are hearing is common Rx300 characteristic post 100,000km.

Due to below standard strut mount used in assembly of front struts..

Ticks me off when manufacture knows this and yet woun't issue recall... Guess no liability to them due to defect or they would have sent out notice already.