I just bought a 2004 HCH and I was wondering what the best tire pressure for the car. I feel like the ride is soft and smooth now, but I have read that its possibe to achieve better mpg performance by increasing the tire pressure. I was wondering who has tried this and what their experience has been.

MilkandCheese

-Dairy products gone bad-

"Remember kids ...There's no justice! There's just... US.....

 

Hi Milkandcheese:

___The best pressure is 1 # less then what would blow it out when hitting the largest bump you would ever hit at the maximum speed you would hit it at

___All kidding aside, if your HCH comes with the max sidewall 51# tires as many HCH’s do, I would take them up to 55 #’s myself. 51 #’s however will do wonders for your fuel economy in comparison to the 35/38 or whatever is listed on the door itself. Pressures this high will add a bit of harshness and probably add a few feet to your emergency stopping at 38 or so #’s. Besides increasing fuel economy, pressures at max sidewall or higher will contribute to a better handling automobile with less sidewall flex from any steering input at any speed.

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net

 

On my 2004 HCH which I bought last January the door sticker says recommended is 30psi cold pressure front and rear. I drove it off the lot new and they had 32. Sidewall max cold pressure rating is 51psi.

The best MPG I could get at the low pressure was mid 40's.

A few weeks later I brought them up to 51psi cold pressure and noticed 3 things:
*MPG went up by about 20.
*Ride was very hard, especially over those unavoidable larger bumps.
*Although what I still consider a safe margin, steering wander was noticed on the freeway.

On my 5Kmiles oil change I dropped them down to 30psi for the trip to/from the dealer and it felt like I was constantly driving either through a constant deep puddle or shifting sand etc. MPG dropped by about 20.

Just had my 10K maintenence cycle and drove it in with 51PSI tires.
Dealer dropped them down to 40psi.

I've left them there at 40psi now for 2 weeks and noticed:
*Those unavoidable sharp bumps aren't quite so jarring
*Freeway steering wander isn't as noticable
*MPG has dropped (I think by ~4) I wonder about this because at the same time my tires were rotated. Not sure if rotation will have effect on MPG but the next day I broke my all time record to work at 66.2MPG.

I'm not sure if it only feels like I'm struggling harder to gain/hold MPG and sometimes it seems like the car used to do better.
Toss an occasional cooling blast of A/C to lower my average and I'm not sure.

I've decided to keep the 40PSI at least for now.

 

So is an average pressure between where the dealer sets it at, and the maximum pressure allowed by the tire be recommended? Is this something I should even be messing with in the first 1000 miles?

MilkandCheese

"3-d Lo-Mein so realistic its in your face" :blink:

 

Hi Milkandcheese:

___It depends what you want out of your HCH in terms of fuel economy or ride comfort? If you want a soft ride, leave them at what the door shows. At that pressure, you will have a very hard time meeting EPA estimates if ever but the ride will be almost as good as that of a std. DX/LX Civic. If you want maximum mileage and the ability to beat EPA estimates time and time again, the max sidewall will do that for you. Some find a happy medium as apparently Hot_Georgia_2004 has so it is really up to you as to what you are looking to get out of your HCH.

___Here is a suggestion. Why not up the pressures by 2.5 pounds at every fill up after the break in period of lets say 5,000 miles. Keep very close track of your mileage, temperatures, and if the distance traveled was over the same area as the last tank. What you should find is a quick acceleration in fuel economy from 32.5 to 35 to 37.5 pounds and a slower increase as you increase your pressures further. I saw this on the Corolla last year as well. After 32.5, I was seeing an ~ 1 - 2 mpg increase at each increment up to 37.5 pounds. After 37.5 pounds and all the way to 50, I saw ~ ½ mpg per 2.5 pound increase. There is some guesstimation (<-- that really isn’t even a word, is it ) as there is really no way to drive the exact same route in the exact same temperatures with the exact same weather conditions from tank to tank but you will see the jump as you head towards 37.5 and the slowdown albeit still increasing above that.

___As for me, all my vehicles are run at Max sidewall or above. The 4,500 # 4WD Lux SUV received > 33 mpg on the highway the last time I took her on a long drive with a tad over max sidewall (40 #’s in some 35 # rated, 17” Michelin X-Terrains) as well as using a few other setup tricks and tips and hyper mileage driving techniques thrown in for good measure. High pressure tires will get you past the EPA barrier quite easily imho with the pluses and minuses as listed in a few of the posts above.

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net

 

I'll very likely raise to 51PSI again soon, really haven't messed with it for lazyness.
Due to the Grand Caravan being parked for a while- needing brake maintenance among other things my better half has taken to the HCH now but has near zero interest in driving for MPG. We all pile into the HCH now and require at least minimum A/C and mostly freeway travel.

All these are wrecking my tank achievement despite what I do in my daily commute. I'll never catch up at this rate.

So I figured in a couple of weeks the other vehicle will be working and I'll be the HCH's almost exclusive driver once again.

 

Well I just raised mine from 32 to 40; I'm in the middle of my 5th tank of gas.

My door jamb sticker says 30, and my tire sidewalls say 44.

We'll see what I get on my morning commute tomorrow. B)

 

Since the car is brand spanking new I think I am going to hold off for a bit on changing the tire pressure. How many miles should I let the car break in before I move the psi up to say 41?

MilkandCheese. :blink:

 

My sidewalls are 44 and I raised mine to 38 the first week. I have a 5 speed and just got 56.8 at the pump. I really don't know what it would ride like at 30 but to me it rides fine at 38. In the fall I might raise it up to 40 but with temps. in the 90's I'm not going to go over 38. Kevin

 

Well I'm not very impressed.

I got 61.3 on my first morning commute with 40 psi.
I was already getting an average of 59.8 with 32 psi.
(This is the average of all 10 of my recorded trips which included three trips at 61.3 already)

And the ride is much more bumpy and noisy.
I'll leave it at 40 all week and reevaluate.