305Busa

2 part question.

Ok. here the deal, Im in sunny South Florida and the last couple of days its been "cold" here. Yesterday it was in the 40s and I didnt take the car out but noticed that one side was lower than the other side, so I got in and played with the lowering module until it looked even. Last night, I took the car out of the garage because I knew I'd be working on my bike today. When I got in my car this morning, it gave me a low tire pressure signal and it was the spare. It showed 29 and the rest of the wheels showed 35 which are usually between 42-49. I believe its because of the cold air out. I took the car for a spin and as the wheels warmed up, the pressure went up but the spare didnt move. Do you guys have a way to keep this from happening? Is there something I should do?

Now, back to the suspension. I also noticed that the left side I lowered yesterday was a lot lower today. After thinking about it, I realized that my car sleeps with the left side next to the water heater where its nice and warm. Could the cold air have any affect on the air suspension as well?

I know its a long question but I tried to enter as much detail as possible. Thanks

Craig B

The only thing you could try is using nitrogen in your tires. Costco has it along with some tire stores. I live in the Midwest and check my tires every couple of weeks. Always check them when cold before driving on them...

CEOEngr

Volume of air is highly variable subject to change in temperture and atmospheric pressure. Therefore, a lot of folks are using Nitrogen as it is more stable to those variables.

rominl

iTrader: (4)

put air in your spare and raise it up to 50psi, that will set you good for a while. you don't have to worry about it when it's higher. if you really need to use the spare, lower the pressure

on the air suspension, i can't say for sure. if you want to try, back in the car tonight and see what happens to the other side

305Busa

Thought about backing it in but I think the rear suspension works as one. I know the front is independent. I might try it anyway and see. It's starting to warm up so it might or might not work.

Luxofreak

Keep it at 38-40 psi when it's really cold and you'll be set. Well, really cold for me is 30F-32F.

jmcraney

You should inflate your tires so that they indicate 33PSI (+/- 1PSI) on your car's display when you first start in the morning. Any other inflation compromises the ride and performance and tire life.

A couple of things that you need to keep in mind about tires: The pressure varies as a function of the tire temperature, about 1 PSI per degree F (up for temperature increases and down for temperature decreases). And the tire is always losing air by a process known as permeation. A permeation rate of up to 1PSI per month is considered normal but typical rates are slightly less than 1/2 PSI per month.

If you benchmark your tires at 33PSI that establishes the warning threshold at about 25PSI. The benchmark process is on a per tire basis so keep in mind that the spare is being included in that.

After you benchmark your tires, including your spare, at 33PSI raise the pressure in your spare to 40PSI. That will allow you about 18 months before you have to add air to your spare again to compensate for permeation. You must not benchmark the spare after it is inflated to 40PSI as that would set the warning threshold to about 30PSI and would be problematic on cold mornings. Once you benchmark all tires at 33PSI don't touch that Benchmark Set switch again unless the battery is disconnected.

You will need to keep adding air to the tires that are on the ground when the TPMS display shows that they are 31PSI or lower when you start up in the morning. You will find that as you transition into Summer you will probably not have to add much air. But when you transition into Winter the tires will be about 4PSI or more low on that first cold morning. If you inflate the spare as I suggested it will not be a problem when it gets cold.

305Busa

JM, I have 22s on my car and the pressure is way higher than the stocks. I know before they read at about 32-35 with stocks and the day it left the shop, it was at 49 with the 22s. But its gone done to between 42 and 49 since then. I just thought that it was off like that due to it being colder than normal here. Its usually in the high 80s or low 90s, even at this time of the year and I know it was close to 100 the day the wheels were put on.

jmcraney

The pressure goes up and down about 1PSI per 10 degree F temperature change and the leak (permeation) rate of up to 1PSI per month is considered normal. This applies to all tires.

rominl

iTrader: (4)

it could be off by that much. couple years ago, we went for a trip, when leaving, tires were about 38psi. at destination early next morning, it was about freezing (29 degrees), and pressure was down to 27psi and tpms triggered

VA380

I ride 22's, and my rear right tire slowly has been losing air since late November. I thought it was just the cold air, but I had a small air leak ... so i had bead sealer put around the rim/tire, worked like a charm.