EpikYummeh

Hi all,

Since I got my 8 in the summer I haven't seen the TPMS dash light come on before as I keep an eye on my tire pressure, but recently with the temperatures reaching 20-30 degrees F I've been having the TPMS light come on.

I read somewhere that for every 10 degrees the temperature drops your tires lose 1 psi, but I haven't noticed any bulging of the sidewalls that would indicate unnecessarily low tire pressure.

So my question is just to long-term owners who have driven their 8 in cold and hot weather what your experience with the TPMS light is and if this behavior I'm experiencing is normal.

Thanks!

paimon.soror

iTrader: (15)

Very common. Don't rely on 'bulging sidewalls' as a method for determining tire pressure. You'd be surprised how low OEM tires (RE050A's) can go before any 'bulging'

Harlan

iTrader: (3)

Completely normal. Since the TPMS light bugs me I keep a bicycle hand pump in the trunk in the back. If the light comes on I'll get where I'm going then top off the tires. Only takes a couple of minutes since you're only a pound or two low, but it's nice to have the TPMS light in case you actually run over a nail or otherwise have an actual low pressure. Also I live in TX so a 60deg temperature swing day to day is not uncommon.

EpikYummeh

Thanks guys! I've all sorts of miscellaneous car care items I need to buy, and a tire pressure gauge is among them.

04Green

iTrader: (1)

Buy a good one. spend $20. Something like this

ken-x8

I have a strong preference for digital gauges, for about the same money. One that has a straight air chuck.

Definitely keep away from the traditional cheap pencil type with the stick that shoots out.

Ken

gwilliams6

always check your tire pressure often, as the ambient temps change, so will your air pressure. Check them when cold (before driving them which warms them up) so you get an accurate reading and know how much air to add. Failure to do this as part of your routine maintenance will spell a shorter life for your tires and possible dangerous driving conditions for a sports car and spirited driving, long before the TPMS comes on.
What do you think drivers did before cars had TPMS ? LOL We regularly checked our tire pressure ! I also weigh in on getting a good digital pressure gauge. I actually keep two in my car, or just keep a spare battery for it so you aren't without one if the battery dies after a year or two.

Jedi54

iTrader: (7)

I bought this years ago and it's been great

EpikYummeh

Looks good, I'll think about it.

ken-x8

TPMS isn't a substitute for checking tire pressures. The pressures at which TPMS goes off are really far from where the pressure should be.

TPMS is a substitute for (and improvement over) noticing a roaring sound as the car begins to randomly swerve.

Ken

srx600guy

cold air becomes denser and therefore shrinks (which is why people love old air intakes btw) so these guys are right, during the winter you need to fill up your tires a bit more

JamesD31

Just buy a digital tire pressure (or analog) for like $10 and use it? Fill up tires when cold but never fill up to max pressure.

AbortRetryFail

I've been driving an 86 RX7 for the last 11 years. The truck yard/parking lot at my work is bristling with dropped screws, nails, and other hardware. I've lost plenty of tires because I picked up a nail and didn't realize it until I'd already gone 5 miles on a low tire and wrecked the sidewall.

This morning my 05' RX8's TPMS light and buzzer came on from the cooler temperatures. Right rear was down by 2 PSI.

I am totally sold on the utility of this system!

CRAZ8

Never seen the light once since I bought mine in '07, and it can get pretty cold around here.

Jazzmeson

iTrader: (5)

Pretty common, I keep mine at 32 psi for several months. Until winter hit and the weather average went down almost 30 degrees. TPMS went on and all my tires when down to 27-28 psi.

Posted From RX8Club.com Android App

EpikYummeh

Yeah so I got a tire pressure gauge. Front left was at 25 so I filled the front to 30 psi and the rear to 32 psi.

gwilliams6

No advantage to having the fronts at a lower psi. The car is designed for better balance and handling with equal tire pressure all around, they should all be at 32 psi. Always adjust as ambient temps change. Only nitrogen filled tires wont have psi be affected by temp changes

EpikYummeh

Thanks for the tip. In looking at other threads on the forums here 30 front and 32 rear is what I saw most often so that's what I went with. Next time I fill them I'll make sure to fill them all to 32 psi.

JamesD31

It doesn't matter really how much you fill them. Filling them to ~30 PSI is used for racing; normal street driving I suggest having them higher ~40 (if max is 50 psi).

The air condenses, so that is why when it gets cold, when you filled it up to ~40 psi in the hot weather, it now drops below that psi and triggers the TPMS. Always fill tires up when cold.

j9fd3s

i'll use an example from the race car, it doesn't strictly apply, but we measure pressure and temp, so i have numbers...

lets say we pull a set of tires our of the trailer, and they are at 40F, and we fill them to 27psi.

when we put them on the car, and heat them up to 180F, the pressures will come up to 33-34psi.

so yes, temperature does affect pressure, quite drastically.

the car does know this, but it wants 32psi cold.

swoope

iTrader: (5)

wow,

lots of stupid here..

the recommended tire pressure is right in your door sill.. find it..

set the tires to that pressure..

when it gets cold the pressure is going to go down.. if you drive on track it is going to go up..

adjust accordingly..

duh!


beers

logalinipoo

My door plate is blank

swoope

iTrader: (5)

wow,

mine to.

10/03 build..

so i put 34psi in both front and rear..

when it gets cold.. and the tpms goes off i move to florida. and if it goes off again i adjust the pressure to 34 psi.

and when it gets warm again i keep it at 34 psi..

when i go to the track it set the front tires to 30 cold and the rear at 32 cold.. and then when i come off the track i bleed them down to 40 psi.

when i get home from the track i set everything back to 34 psi..


beers

logalinipoo

Mines 5/04. But my tpms hasn't worked in years. It stays solid all the time. Discount tire said they had bad batteries so i had them changed 2 months ago and tried the reset worth no luck. The light is on all the time. Ive tried pressures from 40 down to 20 and no luck.

Any ideas. Ive read solid light is low pressure and blinking light is no communication. Even with the bad batteries it was a solid light.

swoope

iTrader: (5)

seems your issue is bad sensors or no sensors. do you know they are in the wheels.. my sensors are stock from 03.

there is no reset. it just happens..

my wheels were off for 3 weeks. sensor lite was lit on dash.. drove for 15 min. it went off..



beers