I've heard ranges from 35 to 45..... what number would be the best compromise between fuel efficiency and safety?

 

Hi Se7,

I have had our Fit since April, 2008. I have experimented with the reg 32 psi, and then 35, and then 40, and for the most time at 45 psi.

I find the ride to still be very comfortable, and the handling to be even better. But the gas mileage at 45 psi is outstanding. I get over 40 mpg, and not driving slowly either.

There are Fit drivers out there who are getting well over 50 mpg, and even a few getting 60 mpg, and recently one fellow at 70 mpg.

Give it a try!

 

70?! Oh my gawd! I've been averaging about 35 to 40.... I had no idea how much psi effects mpgs.

Thanks a lot for the heads up.

 

There is NO WAY that tire pressure is going to double your mileage. Also, running over-inflated tires seriously degrades the traction/handling/safety capabilities of the tire, and you will bald the centers of the tire. Sure, you may save a couple MPG, but that is offset by wearing our your tires in half the time. I could never understand why people do this.

I am of the exact opposite theory. The tires are your most important safety component of your car giving you traction with the road. If you cannot stop or handle as well as the car in front of you in an emergency situation, you can do a lot of damage (for which you will be at fault). How much is body damage or injury or death from loss of control worth?

Completely false economy in my opinion. Run the tires and alignment as the manufacturer recommends unless you have enough experience to run them otherwise which is likely only to come if you have a good amount of tuning/track experience.

Those getting 40/50/60/70 must be driving like a granny goose. This is the same issue I have with Priuses driving slow to maximize their fuel economy. They disrupt the flow of traffic, causing a safety hazard. Finally, you need to do the math and figure out how much you're saving per hour. Unless your time is worth nothing, you're better off doing something more productive with your time.

</rant>

 

Two separate schools of thought I suppose.

I consistently get about 35-40mpg on city streets and I'm usually going a little bit faster than the speed limit.

It does get difficult HMing on the freeway where people go 85-90+ on a friggen 65 and cutting you off every chance they get.... what the hell? Is it a race or something? Is getting a few yards ahead of me really going to make the difference between life and death for them?

I think I'll try around 35psi and see what happens from there.

 

A more serious answer is you should be running what Honda puts in the door jamb, that is 32 psi for the factory 15" tires and 33 psi for the factory 16" tires. This difference is due to the different load ratings of the tires.

From my initial measurements, Honda's recommended tire pressures are already a compromise of safety in the interest of fuel efficiency. With the stock tire pressures, the rear tires are running too hot in the center which indicates over-inflation (which will lead to balding the centers first) as well as reduced traction/handling/safety. I have already DROPPED the rear tire pressures to even out the temperatures.

 

i go by the rating of what's on the tire.

ie- if max tire psi is 41, i'll be at 38.

 

I do agree there is no point to racing to get where you're going. I usually "go with the flow" and not try to disrupt things. This causes the least "turbulence".

35 psi seems reasonable if you are really intent on trying to maximize your mileage, but note that you WILL bald the centers of your tires first. The lower the profile of the tire, the more sensitive it is to incorrect tire pressures. With the 15" 65-series, it's less of an issue. With the 16" 55-series, you are starting to ask for more trouble. In my Boxster, I can easily tell a difference of 2 or 3 psi (from optimal) having a negative effect on handling.

You might want to leave the rears at the factory pressures as I noted they are already over-inflated. Almost 2/3 of the weight is on the front tires, so reducing the minimal sidewall deflection in the rear tires by further over-inflating them is going to reduce heat generation in the sidewalls by only a trivial amount.

Good luck with whatever you choose...

 

So then, do you choose a tire by its maximum inflation pressure? Different tires' maximum inflation pressures can vary quite a lot and have nothing to do with their load rating and even less to do with the manufacturer's recommended tire pressures (which in many cases are already a compromise).

 

Hey stan man how are you getting over 40 mpg. I also have an 08 sport m/t. I can't seem to get over 37 mpg, and that's not going over 65 and not revving above 3000. Can you please advise.

 

Pretty much as soon as I got my fit I pumped the tires up to 46psi. I'm getting on average 46mpg right now.

WOW I didn't even realize until I just posted this that they are the same number ha ha!

 

is that all you did is increase pressure in your tires to get that kind of mpg.

 

No way. I changed my driving habits quite a bit. The fastest this Fit has ever gone is 70mpg and that was one time on the interstate, other than that I never go above 55 (speed limit) on the highway. I don't think I drive like a granny though, I just drive the limit and try not to use my brakes. I am probably 70% highway driving, my driving consists mostly of my commute to college.

 

I already had issues with the TPMS light on my '09 Fit Sport on another post. At 32 psi, I got much lousier highway MPG than at 40. Imagine that. I just adjusted the tires to 35 and sense that I'll keep them at this unless I read/hear otherwise....

 

I drive 120 miles a day. 90% highway 10% city. 32psi, i don't go over 65-67, don,t rev above 3000 when changing gears. No a/c, the best i can do is 37 mpg. WHAT AM I DOING WRONG?

 

I never rev above 2k and my tires are inflated to 46psi, I might increase them more actually to max sidewall. I don't use AC either and drive 75 miles a day probably. I never go above 55 and accelerate/decelerate slowly. Are you driving an 09? 09's get better mileage.

 

My Fit Is An 08. Is All That Over Inflation Good For The Tires?

 

It's not over inflation. Over inflation would be going over max sidewall which is 51 I believe. 46 is still well below that.

 

WTF?

The maximum inflation pressure is 51 psi per the tire manufacturer. That is the maximum inflation pressure under any conditions where the tire manufacture will warrant it against failure. Where does it say that anything under 51 psi is not over-inflation and therefore safe?

Under-/over-inflation is specified by the car manufacturer. Anything over the recommended 32 psi or 33 psi is considered over-inflated per the car manufacturer.



What parts of the owner's manual are not clear: "Using tires that are excessively worn or improperly inflated can cause a crash in which you can be seriously hurt or killed." "Overinflated tires can make your vehicle ride more harshly, are more prone to damage from road hazards, and wear unevenly."

Furthermore, the maximum inflation pressures are that. Maximum. They are not maximum cold when you check them. Per the manual on page 274: "If you check air pressures when the tires are hot [driven for several miles (kilometers)], you will see readings 4 to 6 psi (30 to 40 kPa, 0.3 to 0.4 kgf/cm2) higher than the cold readings. This is normal." So, inflating to 46 psi is not "well below" and quite likely at or above the tire manufacturer's maximum permissible inflation pressures when hot.

Some of you guys are really funny. Think about how well you'd do trying to make a claim on tire wear with Honda or any tire dealer. Likewise, if you're in an accident, you'd be treading on thin ice if the cause of the accident can be attributed at all to your knowingly under- or over-inflating your tires.

 

This has been discussed extensively on other parts of the forum.