Lomag

Hey Guys,

I searched around and I'm amazed that I couldn't find a straight answer for this question: What tire pressure do you run for 19" wheels on your 545i?

The obvious answer is to look on the door jam or read the owners manual. The results are:

2004 Manual: 32/35 (max 4), 38/42 (max load)
2005 Manual: 32/35 (max 4), 38/42 (max load)
2006 Manual: 35/39 (max 100 mph, max load), 30/38 (max 4, >100 mph), 36/44 (max load, >100 mph)

It seems like the confusion comes from the 2006 owners manual not matching with the prior years. The 545i hasn't changed, why have the recommendations changed? And what's with the <100 mph and >100 mph recommendations in the 2006 manual?

I've been running 35/39 and I think these pressures are NOT good for me. I have a wierd bounce type feeling like there's no traction in the back when running over certain bumps which I've been trying to solve for months now. I had this happen on my previous 18" Style 124 rims however at that time the tires were completely worn, now, they are still vitually brand new. I just had all my wheels rebalanced on a Hunter GSP9700 which cured my high-speed vibration/wobbling issue. Apparently the original tire shop did an awful job balancing my wheels. So, I'm pretty sure the wheels are OK which leads to me look at the tire pressures.

It seems to me like I should try the 38/42 recommendation. So what do you guys think? What pressures should I run, what pressures do you run? Let's come to some concrete conclusion on this one!

tachyon

Hey Mark -

The door plate in my 550i sport (18" 124s) shows 30 psi front and 35 psi rear. I presume this is for the run-flats, which now are gone. I typically run 32 F and 34 R with the winter tires I have on the OEM 124s, and that seems to work well.

With my summer-time 166s right now I have them at 36 psi all around, and that works well, but it does feel a bit firm now and then on the Chicago-area roads. I did run at 32 psi all around for a while and that was excellent for the rear but a bit soft for the front. So maybe the right mix for the summer shoes is 34F and 32R (or maybe 34 all around).

Now that you've brought it up ... I may experiement some more before the cold weather sets in.

lanikus

Hi,

You should look on the homepage of your tire-manufacturer.
You should always run the tire-manufacturer's recommendation.

E.g.:
- for my 525d, Vredestein recommends 45PSI front + rear for my 19" ultrac sessantas
- for your 545i, Vredestein recommends 48PSI front + rear.

Look http://www.vredestein.com/Onlineadvies_Adv...voeringID=19501

Cu Lanikus

Rudy

I disagree completely. The tire manufacturer will list the maximum pressures allowed for safe operation -- that's all. You should always use the car manufacturer's recommendation since they were the ones that engineered the entire package.

The tire manufacturer doesn't even know how much the car weighs, what type of normal load the car has, etc. Clearly, it's much better to only use the markings on a tire as a guide for maximum pressure...

olli_535d

The pressures listed on the Vredestein site are way way way too high.

Agree with Rudy on that one. If you're bouncy at 40psi, what do you think 47 will do ?

I have several times contacted the customer service department of two different tyre manufacturers and with the car details, wheel and tyre sizes, they always came back with properly calculated figures. The manufacturers were Toyo and Continental.
Both came back with proper min/max values (higher rears) and using a medium setting of these, have been spot on.

Lomag

I've bumped up the pressures to 38/42 this morning and after about a 50 mile drive it seems to be much better although there still is a slight shift over larger bumps but that might be normal to a certain extent. It's much better with 38/42 than my previous 35/39 pressure setting. I'll drive around for a week and see for sure. On the other hand, the lower recommendations of 32/35 would be much too soft so I'll probably stick with 38/42 from here on out.

znod

I start with 36 f and 34 r and let them go down to 32 f and 30 r.

lanikus

Rudy, the recommendation of vredestein is the same as BMW recommends on the door-plate: for my ride it's 3.1 bar on the back which is equal to 45PSI.

Look on this picture of my door-plate:


For low-section tyres it's IMPORTANT, to inflate the pressure given for full loads or high speeds. Therefore I think 45PSI is NOT too much -> it's the right pressure to avoid serious damage to the sidewalls of the tires which can lead to serious accidents!

You can also read more on this here: http://www.vredestein.com/Onlineadvies_vee...99&FaqID=10

Cu Lanikus

Rudy

Fine, they happen to agree. My point was that many people look at the maximum pressure stamped on the sidewall of a tire and think that's the pressure they should use on any car it's mounted on. That's the mistake I see many, many people making and that's what it sounded like you were saying in your earlier post.

I'm not questioning the importance of proper inflation (low-profile tires or not), in fact I agree that it is imporatant to keep the inflation pressures correct at all times. I'm only saying that you should trust the car manufacturer and not the tire manufacturer when determining the correct pressure of the tire. (If they agree with each other, fine. If they disagree, use the car manufacturer's figures...)

On the same Vredestein website you linked to, you'll see that they agree with me on "Tyre Tip #1":
http://www.vredestein.com/Onlineadvies_Ban...sionID=89751399

(since the Vredestein site uses flash, the above link may not work once my session expires so here's the quoted text or look on the site for "Tyre Tips" or "Online Advice")

olli_535d

Is it really? your door plate recommends max 2.6 bar front and 3.1 rear. the web recommendation on the Vredestein website is 3.1 and 3.5 front and rear.

That's 48f and 51r over the BMW max recommendation of 38f and 45r

I run 36/40 under normal conditions (2 people in the car) and go 2f and 3r psi higher for the family holidays.
I have perfectly even tyre wear, which also indicates correct pressures.