[str86diesel]

Hello all,

Currently I am running some 19" HRE Flow Form wheels with low profile valve stems and Continental DW06 tires. Usually in Summer I run my tires around 45 psi to get better fuel mileage and as the weather was getting nicer where I live, started noticing that I am loosing about 1-2 psi per tire per day. I watched them all summer trying to figure out what is happening, tried soaking them in soap and water to find the leak and nothing. Had a tire shop take a look and they too cannot find anything. Apparently the leak is just to slow to find, but again, it is with all tires.

Has anyone ever faced this before or know what could be the problem? I don't suspect that I have 4 bad wheels and I am wondering if its worth it to have a tire shop just swap out the valve stems. Any ideas are appreciated.

[MickAv8r]

A) 45 PSI seems rather excessive. The spec for the car is about 10 PSI lower. At the track Im usually taking air out once they venture above 40-42 hot.

B) what are "low profile valve stems" are you running the oem TPMS sensors or just some aftermarket part? who made them?

[str86diesel]

Originally Posted by MickAv8r

A) 45 PSI seems rather excessive. The spec for the car is about 10 PSI lower. At the track Im usually taking air out once they venture above 40-42 hot.

B) what are "low profile valve stems" are you running the oem TPMS sensors or just some aftermarket part? who made them?

A) The tires say that they go up to 55psi and I find that when i run more air in them around city, I get much better fuel milage. On a warm day they might warm up to about 48 degrees.

B) When i bought the wheels they said that the normal valve stem would rub so they gave me shorter ones that that they call low profile for free. they are metal valve stems vs the traditional rubber/plastic ones

[BUFFLARS12]

Could be one of three things....the valve....corrosion on the bead of the wheel.(between the tire and wheel)....or you mind/ability to check the psi correctly. If your checking with a gauge your probably leaking some out.
I vote for the last option.

[str86diesel]

I typically fill them with air and check them with a gauge initially to make sure I have them all in the same range. Then as I watch the TPMS monitor usually it is about 1 psi off. The computer usually shows them at 44 psi. Through the week (NOT using a gauge) I watch the tmps computer and every day it shows less and less air, usually loosing between 1-2 psi per day. Usually by the end of the week the tires are down to about 35-38 psi.

[Wires]

For the record, the 55 PSI on the tire is the maximum pressure for the maximum rated load. That has nothing to do with an "approved" value for your setup.

All 45PSI is going to do is wear out the center tread of the tire, while never using the outsides. You'll save a couple bucks in fuel costs, but will pay 10 fold in replacing the tires sooner. Handling at 45PSI is brutal. It would be twitchy with poor traction.

If the weather has just gotten cooler, it is common for tires to leak a bit during that transition. It's pretty much impossible that all tires are simultaneously defective though.

If you want the actual answer, check the tire pressure on COLD tires with a gauge. Then check it again in a couple days (week?) That will give you an accurate answer, and much better than mixing the gauge with TPMS.

[lens]

Originally Posted by Wires

For the record, the 55 PSI on the tire is the maximum pressure for the maximum rated load. That has nothing to do with an "approved" value for your setup.

All 45PSI is going to do is wear out the center tread of the tire, while never using the outsides. You'll save a couple bucks in fuel costs, but will pay 10 fold in replacing the tires sooner. Handling at 45PSI is brutal. It would be twitchy with poor traction.

If the weather has just gotten cooler, it is common for tires to leak a bit during that transition. It's pretty much impossible that all tires are simultaneously defective though.

If you want the actual answer, check the tire pressure on COLD tires with a gauge. Then check it again in a couple days (week?) That will give you an accurate answer, and much better than mixing the gauge with TPMS.

I never understood why people don't understand what the psi on the tires mean. It's simple, follow what your door jam says and you'll be fine. High psi(40+) will wear center as it's overinflation, low psi (below 32psi) will cause underinflation and wear the sides.


45psi is way too much. Keep it under 40 and above 32.

[scostu]

http://cache.bmwusa.com/pdf_6117e873...e-107286b35189

..... recommendation per BMWNA manual for tire pressure.

pg 194

[IndotagSwizz]

your problem is 45 psi and that much pressure on your tires by the way is going to wear out your front suspension prematurely because you are already on low profile tires and at that pressure your tires are a brick wall not taking much cushion making your suspension do all the work, I bet when you hit a pothole it sounds like your car just got hit with an RPG

[str86diesel]

I hear what you guys are saying about the tire pressure and I will lower it. But I am still concerned on why all of my tires seem to be losing air. On Friday I checked my tires and they were sitting at 41psi cold. This morning I got in the car and the TPMS said 33 and was telling me that I had "low pressure" in the tires and was alarmed (my TPMS usually warns me of a flat between 32-33 psi). Yet the car sat in the garage all weekend and wasn't driven.

[wdeerfield]

sounds like they are not mounted to the wheels well and you have a slow leak probably at the bead. i would have them remounted and have the inner lip of the rims cleaned to ensure a proper seal.