My tire pressure would get very low within a month or two of driving. Is this a common occurance for all tires?

 

This is not common for all tires. You should not be losing a whole lot of tire pressure in a month. You should check for a few things:
- Leaky valvestem
- Puncture in the tire
- Bad bend in wheel (you would know about this pretty easily)
- Crack in wheel

If you can't find any visible sign, get soapy water in a spray bottle and spray down your ENTIRE wheel. If you have a container big enough you can dunk the whole think in water as well to see where the air is leaking from.

 

It's not just 1 tire but all four. Two are pretty new. Could it be due to temperature fluctuation? My area gets pretty hot some days.

 

Hmm... Well you may be able to rule out a couple of those if it is all four. Temperature could play a part but if you're saying your tire pressure gets very low after a month or two that doesn't sound normal. What PSI are you talking about when you say it gets low?

 

When the TPS light came on, the pressure was at 23 PSI for fronts and 30 for rears. I normally fill my tires to about 4-5 PSI below the max. Front tires are Toyo Proxxies, rears are Good Year F1s.

 

Wow, I wouldn't leave it to chance that two separate make and model tires are leaking on all four corners. I'm going to guess leaky valvestems.

 

My guess is valves as well.

 

How much would a stretched tire play into this? He says he fills 4-5 psi below max psi, so that sounds like something above 40 psi. Add in the factor of the warm to hot days and cold nights of California.

 

If the tires are stretched and there is dirt or debris around the bead/bead seat, it could leak air too.

 

The TPMS (Tire Pressure Monitor System) light in my car blinks for a minute and stays on even though my tires are at the correct PSI (33). I bought my car (06 g35x sedan) used and I've read that when you change the stock tires the TPMS needs to be reset by the dealer. I really dont mind it because I'm going to get new tires soon and it would be a hastle to take it in and reset it every time.

 

Check the pressure in the spare.

 

if you're stretched it's a lot harder to get a good seal. one of mine leaked for months and didn't get totally solved until my 5th trip back to the tire shop. they replaced all the valve stem, orings, reseated it, but finally they found out they had to totally smooth out all the little prongs on a stock tire and then use some sealant to get it to not leak. not the absolute prettiest fix with the sealant, but a whole lot better than constantly going low

 

+1

The beat seat has to be real clean to hold air on a stretched tire (depending on the stretch).