Help! Tire pressures..

[CJ]

I put some wheels on my girlfriends fathers E39 528i tonight, 16" 540i rims with Toyo 205/55/16 tires on them I beleive. Anyhow, we went to the gas station and filled them up to the recommended specs. 29 front and 33 rear. And they look REALLY flat.. I double and triple checked them, the pressures were correct. Any ideas? Thanks.

[SilverStreak]

Where did you find the recommended specs? On the tire? One the 528? 540? Maybe call the place where you got the tires, ask them?

They shouldn't "look" flat, but sometimes if you're used to looking at 40 series tires, etc, taller tires like 55 series have a tendency to "look/appear" low on air cuz it's more noticeable. My wife's CL-S have 215/50-17's on it and they always look low, but they aren't when I check them.

I suggest double checking the recommended specs, and maybe consider bringing an extra pressure gauge next time, to be sure the one you're using is accurate, etc...

[Dark Helmet]

hmm, i think they should be 225/55s, but otherwise, is yoru guage good?

[CJ]

The recommended specs are by the car, the 528 suggests them in the door frame. The tires are the correct size, and I am used to looking at 50 series, these simply look FLAT. If I saw someone on the road, I would tell them they look flat and dangerous...
I also checked with 2 tire gauges, the one I use, and th eone at the gas station and they are both the same. So I am lost..

[SilverStreak]

Wait. The specs on the 528 are for what size tires? Same size as the ones you just put on them?

That's what you need to find out- the recommended specs for those exact size tires you now have on there. They could be different size tires than the OEM ones that came on the 528, and therefore, different psi....

[Dark Helmet]

yes, if the OEMs are 225/55 and you are using 205/55s then you would easily ride too low on 28psi.

thinking back to chem/physics, and fluid-dynamics etc....

the smaller "contact patch" will compress more with the same force applied from above and the same internal pressue as there is a lesser sum of energy inside the tires....

where's rukmen when you need him!!!!????

[CJ]

Sorry, they are 225/55/16's, mis type.

The door jam sticker says those are the recc. PSI's for 15", 16", and 17" tires in thier proper respective tire sizes..