I was wondering about what's the correct tire pressure for my size 18's of my 528i. I never used 18's before so I hope you guys out there can recommend the proper pressure for comfort and economy. i got 18 245/40 all around.
FYI...the BMW recommended staggered tire sizes for the NON M5 e39s (if you have an 03 owners manual or if you have a 2003 e39 sport...the label on the driver's door jamb reads:
235/40/18 (front)
265/35/18 (rear)
And as others have suggested...a 245/40/18 tire size also works or you can go with the M5 rear staggered tire 275/35/18. If you run all these numbers thru a tire calculator (once again already mentioned)...you can get an idea of what the circumference/diameter of all these tires are...and how much rolling difference each one has compared to the original circumference/diameter of the OE tires. You want to stay within 3% (+/-) between the axles...greater differences can create problems with ABS & the car's traction control systems.
Below is the tire size/inflation pressure chart from a 2003 540i/6...note the BMW recommended 16"/17"/18" tire sizes (image by chiefwej):
You must also take into account the load rating, and adjust up or down accordingly.
Note that all the tires in the above table are rated 94 or 95. If you buy tires that are rated, say, 97, you must adjust the pressure down, or the tires will be overinflated.
I normally run 36 psi all around on 235/45-17s, which have been rated 94. I recently bought a set of GY F1 Asymetrics, which happen to be rated 97. I had to adjust the pressure to 33 psi because of the higher-rated (over 200 lbs difference) tires.
Hello All,
Question: I recently had all new Bridgestone Potenza RE970AS Pole Position All season 97W XL rated tires installed. Put the tire pressure according to the door jam label 33 psi front and 41 psi rear.
My problem that I am experiencing is a rather very sensitive bumpy ride . I feel every road imperfection on these new tires. The tires are very quiet and handle fine. During new tire install my 2003 525i had a new alignment and new tires road forced balanced. My e39 is equipment with OEM sport suspension. The suspension shocks show no symptoms of being worn out. I have 130K on the vehicle all stock. The bumpy ride is even at low speeds under 20-30 mph, every small imperfection on road is felt.
Could it be simply be that these tires are just bumpy (hard sidewalls) not really good in cold weather , specially on a OEM sport suspension OR the following ?
1. May it be a possible shop did not torque wheels to recommended spec 88 lb ft ?. I also have a OEM security bolt on each wheel.
2. Tires/wheels were not balanced right ?
3. Tire out of round ? I purchased these from tire rack.
4. Slight bent wheel or lip ? I assume this would have been noted during tire balancing.
5. Any possible suspension issue ( ball joints / controll arms) this area I am not to good on checking on the car myself should I take to a shop for inspection ?$ but no clicking or shaking with suspenstion
6. Change tire preasure because these are W rated tires ? I currently have the BMW recommended tire preasure. Tire manufactures maximum pressure is 50 psi. I am try the suggested 33 all around psi because they are 97w rated.
7. Have all of the above inspected in the following order. Please provide any suggested order.
Any thoughts/advice welcomed please.
NEW TIRES: on OEM style 81 wheels 17x8
http://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Potenza+RE970AS+Pole+Position
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