Which part? I'd like to learn more about it.

 

Note the consensus found here

https://www.fitfreak.net/forums/eco-fit/

 

Start by inflating tires to the recommended pressure written on the door jamb.

Then go out and buy an inexpensive tread depth gauge:



Put some mileage on the tires and then measure the wear difference between the center and edge of the tread. If there's a difference then adjust the pressure to correct the wear.

- Add a few PSI if edges wear more than center.
- Reduce by a few PSI if center is more worn.

 

Ahhhhh... a nice sensible post. Thanks.

If you don't want to wait for tire wear to occur (and be measurable with a tread gauge), you can also use a temperature gauge. It's unlikely that you will have a tire pyrometer, but if you have an infrared temperature gauge, that will also give you a very good approximation. After driving (relatively mellow), if your tires are overinflated, they will read higher temps in the middle. If your tires are warmer on the shoulders, that means underinflation.

Note you can also have some variation across the tread due to angling of the tire (camber), especially the rear. For example, if the outside of your tread is -5 degrees compared to the center and the inside is +5 degrees, your inflation is reasonably good (-5 0 +5). If OTOH, the relative temperatures look like -10 0 0, then you're overinflated. With even tire temps across the tread, you will be very close to your maximum tread life and maximum traction.

 

My experience (gained from 44 years of driving) is that the automakers generally lean a little bit toward a softer tire pressure in order to improve the ride quality. I don't know about the Fit, but this was true of both my '03 Sentra SE-R Spec V and my '91 Civic. I kept 35 psi in all four tires on both of those cars (that's 2-3 psi above the manufacturer's recommendation), and found that it improved both the handling and the wear. In fact, after I bought the last pair of tires on the Spec V, I took it in for tire rotation after 10K miles and the guy said there was no need to rotate them, as there was absolutely even wear across the tread on all four tires.

 

Better tire depth gauges don't cost much more and last virtually a lifetime. Way easier to read and more accurate.

 

Yes. There are many styles.

 

i thought psi just depended on what the tire youre running says on it..

 

^I wouldn't go by just the number on the tire. That tire probably fits many cars of different weights and characteristics. You are better off following the pressure recommended from Honda.