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SodaJerk
09-21-2003, 06:44 PM
I was checking tire pressures for my 2003 4.4 this weekend. I had never checked it and I have had it for about 6 weeks now.

I should have checked it upon delivery as all the tires were set to 40psi. :mad: I had assumed that the dealer would have set it properly, but I suppose that was asking too much.

I should have guessed that the pressure was incorrect when the X5 was darty on the highway. It handles much better now.

In any case, I was looking at the door jamb label to determine correct tire pressure and I got a little confused as to what is the correct tire pressure for the rear tires.

I have the 255/55/18 combination and looking at the label, the fronts should be set to 32 psi (which I have already done). However, there are two different possible settings for the rear tires: 32 psi and 39 psi.

In my other vehicles there is only one setting listed for tire pressures. However on this label, there are three possible settings listed for front and rear. I have cleverly (!) deduced that 61 psi is not the correct setting for my tire/rim combination. And both listings show 32 psi for the fronts.

So, what's the correct setting for the rears?

TIA for any assistance in reading the label.

Terry Kennedy
09-21-2003, 07:26 PM
I have the 255/55/18 combination and looking at the label, the fronts should be set to 32 psi (which I have already done). However, there are two different possible settings for the rear tires: 32 psi and 39 psi.

In my other vehicles there is only one setting listed for tire pressures. However on this label, there are three possible settings listed for front and rear. I have cleverly (!) deduced that 61 psi is not the correct setting for my tire/rim combination. And both listings show 32 psi for the fronts.

So, what's the correct setting for the rears?

TIA for any assistance in reading the label.Ok, here goes. For all tire sizes not marked with a special symbol (triangle, circle or square) use the first row in either table. The first table is for a fully-loaded vehicle (maximum gross weight) while the second table is for a vehicle with an average load. All 255/55/18, regardless of V rated, H or Q Mud + Snow rated, use the first row. The 61 PSI is for one particular tire size - the "donut spare".

According to this table, you use 32 all around for normal loads and 32F/39R for a fully-loaded vehicle. 32 seems a bit low to me, but I've never had an X5.

Make sure you are using an accurate tire pressure gauge - it is common to have a few PSI of error in older or cheaper ones. I like the AccuTire - there is a thread here about various tire pressure gauges.

Dealers seem to set tire pressure to random values - I don't know if they never bother reading the door plate or if they have a "one size fits all" pressure that they use on everything. My car gets reset to 32 all around on dealer visits, despite the fact that the plate says 35F/41R.

Emission
09-21-2003, 08:53 PM
I'd suggest using 34 Front / 34 Rear on your X5 4.4 for best overall wear and ride compromise.

If you want best wear (and a bit more darty), do a 36 Front / 34 Rear and it will keep the outside should of the front from wearing as early.

In any case, check pressures regularly.

SodaJerk
09-22-2003, 09:02 AM
6 weeks, huh? :nono:

:D

Yeah, I know -- too long.

I just got new tires for my wife's ML430 and I got the Smartire transmitters installed while they were mounting/balancing the new tires. I just finished hard wiring the display over the weekend. It works quite well as it tells you real-time pressure and temp for all four wheels and offers alerts when tire pressure excees +/- 5psi.

I wish we could have RDC in the US. I'm not sure why BMW does not offer it here. I guess I will have to go the Smartire route at some point.

Does anyone know if you can retrofit RDC?

SodaJerk
09-22-2003, 09:04 AM
Thank you Terry for your explanation.

suzer
12-25-2003, 01:09 PM
I'm bumping this back to the top, because for Christmas I got a new toy - a BMW digital read out tire gauge. Neat!

I've got the standard Michelin 235 65 R 17 tires on my 2003 3.0. After reading it twice, and then reading this post, the door says 32 all around if not fully loaded (I don't weigh THAT much). Currently the tires read 34.5 all around.

Emission - we've got twinsie vehicles - do you have the same tires, too? What are you keeping your tire pressure at?

Emission
12-25-2003, 02:34 PM
Emission - we've got twinsie vehicles - do you have the same tires, too? What are you keeping your tire pressure at?

I keep my wife's at 34 all around. It rides a bit (tiny bit) harsher than 32, but the tires will last longer (the heavy X5 won't roll over the sides as much when the tires have more pressure in them).

On long roadtrips, I will bump them up to 36 all around.