Tire Question

[Zero_Gamer]

Anyone know why my car dealership sets my tire pressure 2 psi lower on the left side than the right?

When I bought my truck the pressure was 34 right/32 left. After having it serviced today which included tire servicing, it's 36 right/34 left.

I've always set all my tires to the same pressure.

[thesteve]

no thats just bizarre
you should have a front and back spec, but left right should be balanced

[jperryss]

They figured it'll be perfect once you're sitting in the car driving it?

Since they all went up by 2PSI, my guess is they didn't actually check the pressure and just decided each tire needed a little air.

[crazydean]

Sounds like a case of "good enough".

Pro Tip: Always check your tire pressure BEFORE driving the car. The temperature inside the tires will increase from friction created by the tires rolling along the road. This increased temp will result in increased pressure inside your tire. Recommended tire pressure is always cold.

[SignOfZeta]

Because they don't care.

[NightWolve]

In an age of digital pressure testers (I keep one in my car's repurposed ash tray), they should be better about it...

[Zero_Gamer]

Well my trucks display shows the pressure of each tire, so it's too exact to be an i don't care scenario, or just add a little air to each one. 

[SignOfZeta]

I suppose its possible that they are setting the pressure in a service bay where there is an air line on each side and the gauge on one side is 2psi off from the other.

Are *you* using a gauge or are you relying on TPMS data from the CAN bus? I ask because those things aren't always accurate. Just because you see a number that indicates tolerance to .1 PSI doesn't mean its actually capable of measuring that accurately.

[Desh]

I suppose its possible that they are setting the pressure in a service bay where there is an air line on each side and the gauge on one side is 2psi off from the other.

Are *you* using a gauge or are you relying on TPMS data from the CAN bus? I ask because those things aren't always accurate. Just because you see a number that indicates tolerance to .1 PSI doesn't mean its actually capable of measuring that accurately.

This!  TPMS readout is not always perfectly accurate.  Let us no if the actual pressures are off.  When I used to work at a dealer people used to freak out about it.  Even if we set pressures correctly if the dash didn't match they would lose their minds.  So we'd make the dash readout correct which in turn made the actual tire pressures in correct to appease the ignorant.

[Zero_Gamer]

I suppose its possible that they are setting the pressure in a service bay where there is an air line on each side and the gauge on one side is 2psi off from the other.

Are *you* using a gauge or are you relying on TPMS data from the CAN bus? I ask because those things aren't always accurate. Just because you see a number that indicates tolerance to .1 PSI doesn't mean its actually capable of measuring that accurately.

No I haven't verified manually. I'll check and report the results.

[BlueBMW]

Hence why I was so glad that BMW opted to not show numerical tire pressures.  They just did green, yellow or red.  Tire pressure lights were pain enough without customers nit picking over numerical variations.

Then they had to go and do this fancy detailed oil level gauge thingy... Customers would come in "my car is low on oil" I check it and its 1 notch below full on the display meaning its maybe 0.1 quarts lower than max.  But they wanted it fixed lol.

So glad I dont work as a tech anymore.

[wildfruit]

That's odd. My BMW shows the colours for each tyre and a number figure for each in either bar psi or Kpa. But the oil doesn't have a gauge just "ok" or top up. Also it doesn't have a dip stick. I hate that.

[SignOfZeta]

I appreciate TPMS and I'm glad it's on every car now. However I don't see any reason to know your tire temps and pressures in real time. A failure light is all you need, one of them even. Even in a motorsports situation where that info is super valuable the driver doesn't look at it when he's hauling ass, the team analyzes it via telemetry and/or its studied later. My track car only has speed, water temp, oil pressure, RPM, fuel level, and lambda and I don't have time to check those, even in a slow-ass Miata. An F1 driver never looks at anything unless he's changing a setting with only the last %10 of the RPM being visible without menu diving.

Most manufacturers have switched to a wheel speed based equation to determine if deflation has occurred and I'm glad. Now we can go back to running regualar wheels again and TPMS is essentially free. 

[Zero_Gamer]

Well measured them manually and the truck readings were spot on, so I just adjusted them all to 34psi

[SignOfZeta]

Weird.