Sponsored by The Tire Rack

[jameselee]

For a while now, I've been quietly dissatisfied with the way my 135 has handled. I was questioning whether I was memory-inflating how well my S2000s handled, or if perhaps the Performance Suspension was over-hyped (it wasn't really exceeding my memory of test driving the stock sport suspension), or I was just expecting too much.

TLDR: Once I properly inflated my tires, it handles very, very well, and I'm happy.

I remember it being great when I first got it, but somewhere along the way, it became nothing special. I was thinking about looking into sway bars, wishing the 1M were out when I was buying (I'd still be happy to have one!), and pretty bummed that my otherwise awesome car wasn't seeming to measure up in terms of handling.

Well, I had been filling my tires using a pretty old air compressor my mom gave me. I was going to buy a cordless air compressor, but she mentioned my dad had long ago gotten one that she never used & gave it to me. It made a lot of noise, but always seemed to have trouble inflating my tires. I often thought they were "close enough", but somehow forgot how important precisely filling tires can be to handling performance.

The most recent time I tried using it, the compressor was clearly losing the battle, so I ended up going to a gas station (after finally finding one with a working and sufficiently powerful compressor) and making sure I had a bit more (the tires weren't cold) than the 36F/39R (cold) specified pressures.

What a huge difference! I'm completely happy with how my car handles now, and am kicking myself for having gone so long without having checked such a basic thing and made this free "mod".

So, I'm posting this as a PSA, in hopes it helps someone else rediscover the joy and performance I knew was possible from this car.

[jpd]

Good lesson, happy motoring

[Cuz5150]

Glad you learn this lesson. BTW: check tire pressure once a month---> mandatory!

Im running 36psi all around.

[1speedbike]

Every 10 degrees of temperature change is about 1 psi! Go from summer to winter.. 90 degrees to 50 degrees, you're off by 4 PSI! Plus every month is another 1 PSI lost, so you should check regularly

Just curious also if you have stock tires? And any weirdness in the treadwear? I'd just check that too, in case some parts wore quicker than others from the underinflation.

I have non-runflats and had to push up to 38/40 psi to compensate for the mushy sidewalls. Feels better now

[ken1137]

Originally Posted by Cuz5150

Glad you learn this lesson. BTW: check tire pressure once a month---> mandatory!

Im running 36psi all around.

Ditto...you can purchase a decent air compressor at an auto parts store or Target in addition to a pressure gauge (LED). Enjoy the ride !

[bozola]

So am I correct in assuming that the TPMS doesn't detect slow leaks?

[Focusedintntions]

Once you drop below 29 psi the tpms sensor will kick on.

[RimasRS]

Originally Posted by bozola

So am I correct in assuming that the TPMS doesn't detect slow leaks?

It detects but when you are loosing more psi not just 2-5 psi

[Hops128i]

I wish the exact pressure would get printed to the dash display. I pretty sure the TMPS senors report the info. I'm my old C6, the exact pressure was available, it was nice to see how the pressure changed as it was driven.

[blschaefer1]

Get one of these:

http://www.amazon.com/G-H-Meiser-EZ-...3767511&sr=8-3

Clip one end to the valve stem, and it seals and holds pressure. Use your compressor hose on the other. The gauge reads pressure accurately as you fill. Makes life real easy.

Inexpensive too.

[Brahmzy]

So what is the preferred concensus on tire pressure. May differ based on tires, sway bars etc, I suppose.

[Greenkirby21]

Discount tire fills up your tires for free : )

[Tom K.]

Originally Posted by Focusedintntions

Once you drop below 29 psi the tpms sensor will kick on.

Not necessarily as it depends on the baseline pressures at the last reset. It appears that the system allows about a 25% drop before the warning goes off. So even a leak resulting in 26 psi would not trigger a warning if the baseline was 32 - as recommended for the front tires on my '08 ZSP 'vert.

And as Hops128 said, there is no reason why the actual pressures for each wheel shouldn't be available. I suspect that BMW may be afraid some drivers may not understand the normal hot/cold variances - which probably explains the heavily buffered water temp gauge on the E46 and it's elimination entirely on the 128i and E90 328i.

Tom

[Cisitalia]

Originally Posted by Cuz5150

Im running 36psi all around.

Same here 36 psi on all four tires. Takes a little bite out of the understeer. At the track drop the rears to 34 psi for even less understeer.

[Bimmer-Bob]

Learn from my mistake: Check your tire pressure to ensure proper handling!

File under "Duh."

Seriously, though, I just recently found out that some dirtbag stole the tire pressure gauge out of my glovebox. Who does that?

The car had been on a truck from Madrid, Spain to Zeebrugge, Belgium, and then on a ship to Brunswick, GA. And then through US Customs. And then two trips to the dealer and one to Firestone to have tires mounted. So it was stolen at any one of those places...probably not tracking it down anytime soon.

Just ordered another one from Tischer ($20).

[Dackelone]

Originally Posted by jameselee

...So, I'm posting this as a PSA, in hopes it helps someone else rediscover the joy and performance I knew was possible from this car.

PLEASE tell me you reset your TPMS after you put the proper air pressure in your tires.

[Ash83]

Originally Posted by Focusedintntions

Once you drop below 29 psi the tpms sensor will kick on.

are you sure?? last week i got a TPMS indicatore for front left, and when i checked it, it was at 24psi . the other three tires were at ~26psi and they did not got triggered.

[1SerieStud]

Tire pressure is crucial not only for handling, but under inflated tires will run at higher temperatures (risking faster decomposition), wear faster, and will cause fuel economy to worsen. I check my tires weekly right after I perform the Saturday morning wash.

[Dackelone]

Originally Posted by Ash83

are you sure?? last week i got a TPMS indicatore for front left, and when i checked it, it was at 24psi . the other three tires were at ~26psi and they did not got triggered.

I think the system work off of - what the last "target" tire pressure was set too. I know like this last week... my tires were set to 2.3bar and 2.8 bar (front/rears). I lowered the front left tire to 2.15bar and the TPMS went off. I did this to see the new SW icon for the TPMS.

Btw... I did find this pdf on the TPMS system and how it works.

Tire Pressure Control (RDC).pdf


new TPMS icon after latest SW update...

[e34m5]

Fill the tires to the desired pressure. Then reset the TPMS. This now becomes the new base line pressure.

I deflated one tire slowly on purpose to test the TPMS. What I found was a 4 psi difference triggers a warning.

[Tom K.]

Originally Posted by e34m5

Fill the tires to the desired pressure. Then reset the TPMS. This now becomes the new base line pressure.

I deflated one tire slowly on purpose to test the TPMS. What I found was a 4 psi difference triggers a warning.

Interesting. As it took an 8 psi drop to trigger it on my '08 128i, I wonder if the newer systems are more sensitive. What year is your 135i?

Tom

[fourtailpipes]

Originally Posted by Dackelone

I think the system work off of - what the last "target" tire pressure was set too. I know like this last week... my tires were set to 2.3bar and 2.8 bar (front/rears). I lowered the front left tire to 2.15bar and the TPMS went off. I did this to see the new SW icon for the TPMS.

you set your pressures .5 bar different front to rear (7.25psi)!? thats a pretty big gap...