Lower rear tire pressure, Anyone?

Has anyone experimented with lower rear tire pressure. I know BMW say higher in the rear than front. I have started playing with lower tire pressure on 225/60/15 tires. I have been running 32-33 front, 37 or so in the rear and been experiencing wandering during my daily commute over 2 lane roads. By the way, the car seems to wander less with a full tank of gas.

I set the front at about 30 and rear at 28. Have not noticed any difference in "daily drive" handling, The turn in may be a bit slower on a quick turn. However, the wandering seems to have decreased slightly. Also, car rides much better at lower tire pressure, especially the rear wheels.

Any thoughts?

First, I would run about 35 in the front and 38 rear. Reducing rear to 35 if experiencing understeer. I think upgrading the sway bars will decrease wandering quite a bit. At least it did in my car. makes the car want to go really straight. Finally, you should get the front end alignment checked. I think that is the final problem. I'm looking at your mod list and I think some minor suspension work would be welcome for you. I would go sway bars, 17" tires/wheels and then consider springs. Obviously you need good shocks but maybe you want to stay closer to the stock ride height, I don't know.

Hope this helps.

I want to stay with stock wheels and tires and ride height. I may replace front struts as they are original and a bit weak. The upper thrust arms are soft per my indy. May replace in the future. Two shops have proclaimed the suspension (front and rear) OK. It has been aligned three times in 1.5 years. Bridgestone Turanza H rated tires have 10,000 miles with rotation every 5,000.

I just, today, installed Bruno's rear subframe mount stiffeners. Will drive later to see what may have changed. They are supposed to tighten things up a bit. Next will be Bruno's front thrust arm bushing insert and replace the rear dogbones (i think).

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Originally Posted by mholbrook

First, I would run about 35 in the front and 38 rear. Reducing rear to 35 if experiencing understeer. I think upgrading the sway bars will decrease wandering quite a bit. At least it did in my car. makes the car want to go really straight. Finally, you should get the front end alignment checked. I think that is the final problem. I'm looking at your mod list and I think some minor suspension work would be welcome for you. I would go sway bars, 17" tires/wheels and then consider springs. Obviously you need good shocks but maybe you want to stay closer to the stock ride height, I don't know.

Hope this helps.

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Funny, BMW sets mine up with 40 up front 35 in the rear. This helps reduce the slight understeer of the E34.

It would seem that this would ride rather rough. Mine rides rough with pressures above 33 psi. My shocks may be worn though.

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Originally Posted by jplacson

Funny, BMW sets mine up with 40 up front 35 in the rear. This helps reduce the slight understeer of the E34.

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my eperience is the car feels better for me with the fronts more equal tot he rears....in spirited driving it may mean more oversteer which of course none of us want..... :p .My own opinion on my 535 about 35 front and rear in my 235 45 17 fronts and 255 40 17 rears is just right for firm handling and just soft enought to take the edge out of the harshness of low profile tires....Your wandering may be a mismatch of tires,my car got wandery overnight when i swapped a pair of new bridgestones onto the front...they were fine on the back