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[monkey_wrench]

I just installed my new wheels on my 330i, went from 17" to 18".

What tire pressures should I run? They came from tirerack at 35psi all around, but my manual says 29 front and 36 rear.

What should I do? Run them at BMW's spec even though they are a different size?

[Isaiah5411]

Go with the manual. It has the correct pressures for different wheel sizes, loads, and speeds.

[monkey_wrench]

I missed that...thanks!

[John_01]

The pressures in the manual are Too Low if you are using conventional non-RFT tires. Try 36PSI front and 38PSI rear. If the front is too low you will get worse tire wear and worse steering feel.

[monkey_wrench]

Originally Posted by John_01

The pressures in the manual are Too Low if you are using conventional non-RFT tires. Try 36PSI front and 38PSI rear. If the front is too low you will get worse tire wear and worse steering feel.

Holy crap...I've got 32 in the front and 36 in the rear per the book.

[Gary@TireRack]

Originally Posted by monkey_wrench

Holy crap...I've got 32 in the front and 36 in the rear per the book.

You're doing the right thing. Ignore the other poster as he is mostly incorrect in regards to changing air pressure for run flats versus no run flats. You can run higher psi up front if you want slightly faster steering response, but this is not necessary and sometimes results in faster wear in the center portion of the tires.

[monkey_wrench]

Originally Posted by Gary@TireRack

You're doing the right thing. Ignore the other poster as he is mostly incorrect in regards to changing air pressure for run flats versus no run flats. You can run higher psi up front if you want slightly faster steering response, but this is not necessary and sometimes results in faster wear in the center portion of the tires.

Thanks.

And thanks for Tireracks excellent service and fast shipping!
Wheels look great!

[Isaiah5411]

Originally Posted by John_01

The pressures in the manual are Too Low if you are using conventional non-RFT tires. Try 36PSI front and 38PSI rear. If the front is too low you will get worse tire wear and worse steering feel.

I have read things like this many times on the forum while researching the subject before putting on my 19" non-runflats, but...there is no distinction made in my BMW owner's manual between RF and non-RF tires when it comes to inflation pressure. That is either because they are assuming we will replace worn tires with RFs or there is no distinction to be made.

Here is something I posted elsewhere after my research of the subject:

"I just put 19s on my car and proceeded to get beat to death until I finally checked the tire pressures the next day. My BMW tire guy - who has always done an amazing job road-force balancing my tires - had put 44psi in the fronts and 48psi in the rear.

So...I started the search for correct tire pressure. This was the most current thread, so...here is what I found out of the both good and bad, correct and incorrect info provided by forum members.

1) Use the owner's manual that came with the car and the door jam sticker as guidelines.
2) Note: The recommended pressures vary (but only slightly) with the load put on them (passengers/luggage) and the speeds traveled as well as the tire size and speed rating.

For example, my E93 came with 18" runflats as they generally do from the factory. The sticker says 33 psi front/39 rear. The manual says 32/35 with 18s and Sports Package unless the car is loaded with passengers and luggage, then it recommends 33/38.

In the E93 owner's manual, they have 19s listed as being 36/39 if loaded with passengers and luggage at speeds up to 100mph. If you drop the luggage, they drop the front and rears a whopping 1 psi to 35/38. If you add back the luggage and go over 100mph, they bump it up to 38/42psi.

My conclusion: The fronts of the E93 should be around 33psi for 18s and 35psi for 19s for average driving/average loads, increasing them 1-2psi if the car is loaded. The rears should be 35 for 18's and 38 for 19's for average driving/average loads, increasing them 1-2psi for luggage/increased loads...and another 2psi if you're loaded (literally or figuratively ) and driving over 100mph.

Final conclusion: We're talking about incremental changes here but we are not anywhere near the 44/48 that my BMW guy put in or that has been recommended by some on the forum. "

[flip4335]

My door jamb says 39psi front/45psi rear for loads and speeds up to and over 100 mph, regardless of tire (rft/non-rft).

Otherwise, it is pretty low and maybe it works for rft, but I switched and now run 35psi/41psi front/rear in my Hankooks, which feels similar to previous runflats. This is 3psi F/R above normal recommendations.

I attended a special driving course and the instructor said to pump up the tires 45psi all around...where I was eventually driving, the road surface varied, so they wanted us to max out our tire pressure to meet all terrains...

My point is, tire pressure depends upon the situation and performance characteristics of each vehicle and tire.

I found that non-rft tire pressure is a little higher than rfts...especially for those who want the same OEM feeling when swapping tires.

[remmib]

I use 0.1 bar more in the rear.

[VMRWheels]

Originally Posted by HiHoAg

Go with the manual. It has the correct pressures for different wheel sizes, loads, and speeds.

That's what I'd recommend too. Whatever the manual says.