Hey everyone, I own a 2005 Honda Civic sedan. Lately, I have been reading that the best way to improve your gas mileage is to keep your tires properly inflated (and drive slowly, but that's not fun. . .) so I busted out a decent bicycle pump (I've heard that the gas station pumps aren't very accurate) and found that the tires were at 20 psi. According to the plate on the door, my tires should be at 30 so I put them there, but it says that is for "cold" temperatures. Does that mean that the tires need to be cold (as in not driven) or that the temperature outside needs to be cold? Sorry if this is a really stupid question. I'm pretty much an idiot when it comes to cars.

Thanks for the help!

 

Forget using a bike pump, or any pump, for measuring your tire pressure. Use a proper tire pressure gauge.

Also forget what the doorjamb says. That's just a basic rule of thumb to go by with stock tires, and it doesn't even take into account how much weight you have in the car. If you change tires, rims, or weight, that pressure could possibly not be correct.

For the most accurate way to keep your pressure correct, before driving anywhere that day, load the car how it is when you do most of your driving and fill the gastank. Then chalk across the treads and drive the carin a straight line for a few meters. There is going to be a small range of pressures where the chalk wears off pretty evenly. Use pressures in the upper part of this range. If the inner tread is wearing, you need to reduce PSI. If the outer tread is wearing, you need to add PSI. If you load the car down, like for a roadtrip, you'll want to add PSI. If you drive a lot of twisties aggressively, you'll want to add PSI for even wear and less sidewall deflection.

 

I knew I came to the right place...

Guess i'll be heading off to Autozone later on today. Any suggestions about pressure guages? Should I spring for one of the expensive digital ones or will the simple stick ones that everyone is familiar with work just fine?

 

They're bothincredibly accurate... the question is, do you want to spend the extra money for a fancy digital guage (and be a pimp lol) or do you want a cheap, functional one (and not be as big of apimp)?

And the "cold" thing means that you should measure the tire pressure when it's colder out (evening, morning, mid-day if you happen to live in the arctic circle,etc.)

 

Cold pressure means the car has been parked for at least a couple of hours, or driven for less than a mile after being so parked. The ambient temperature should be typical for the season. In winter, the pressure will drop slightly so you do need to add and remove air slightly between winter and summer as well. The same "cold" pressure that is found to be optimum should be used. But you really won't notice that because all tires leak very slowly so you'll likely be adding air every few months anyway.

 

Stick gauges are just fine. I wouldn't drop the cash on a digital one unless you're taking it to the track consistantly... even then its a bit of a stretch imo

 

My advice is the same as mk378 and Forty04. Check tire pressure first thing in morning and use the pressure listed on the doorjamb, assuming you have the stock tires or their equivalent. As to digital vs. analog I would ask you, which is more accurate, a digital clock or an analog one? Use which ever one you feel comfortable with. I use the analog one on my Silca bike pump.