But what would be the explaination for that if I were to try it? I get cornering... the sidewalls are stiffer so it will tend to not to roll over is own sidewall, but in a straight on stop.... Is it just a matter of the nose dipping less? If so, that might feel like a better stop, but is the stopping distance better?

 

This is why I want actual data. What I found was maximum 1mpg difference.... going from recommended psi to max of 51psi. With everything else being as equal as possible.

 

Yes. Stopping distance is improved. It is actually a fine line and the conditions play a big role too. But overall, stopping distance is improved at higher psi. There is a point where going well below recommended does decrease the stopping distance but at the cost of handling.

 

Livvie, you bring up a very good point about the FEH tire pressure and MPG. Many people think it is the vehicle's responsibility to get good mileage, but it can only get you to the water, it can't make you drink.

In my post, I didn't say cranking the tire pressure alone added 13mpg. If you put your tire pressure at 51psi and only get 1mpg better, that's your fault. I've tried to help everyone here and on other sites, get the mileage I do. Tire pressure is only one thing that can lower your mileage, not raise it. Once you get close to 100% out of your vehicle mileage wise, you will never understand what is lowering your mileage. I've never got 100% out of my FEH, but I've came much closer than most. The fact is, I know when my FEH is not close to 100%, I just don't know if my driving will ever be at 100%. I can get a 53mpg tank, but I choose to drive faster with the flow of traffic and except a 5mpg hit. It's not the tire pressure that's giving me the hit, it's my acceleration and speed.

Here is a good example of what tire pressure will do....

Tire pressure allowed me to make better use of my techniques at the MPG Challenge in Madison WI. Debbie Katz has the highest recorded life time average at around 40mpg. She agreed to let me drive her '05 FWD FEH after her in the MPG Challenge if I came to Madison by an Airline. Debbie kept her tire pressure 6-8psi lower than I do I think, so I ask her if she would raise it to 50psi for the Challenge. She agreed, so we both would compare our styles of driving with everything because we both were driving the same FEH, the same distance and route with the same conditions. One difference was I knew how to take advantage of the higher tire pressure. After doing some coasting test, I knew the FEH could coast 36% further in "N" than it could in "D".

The results was, I took advantage of the tire pressure and got 13.3mpg (61.8mpg) better by coasting.

I can only estimate that I would have got ~55mpg with 44psi in the tires. Remember, I drove though town out to the country on a 26 mile round trip in a place I've never been before. BTW, just about everyone in the Challenge had their tire pressure cranked up much more than 50psi.

My guess is tire pressure is only one of many problems causing you to only get a 1mpg increase in mileage. Your not going to get the actual data you want, because I can only tell you an estimate in mileage I lose when my tires lose pressure on the my daily commute.

GaryG

 

Hi Gary,

That is why I asked the question. With everything else being EQUAL... what have people found for mileage increase by increasing PSI (alone). I found only a 1 mpg difference at most. This is NOT to say that I don't get good gas mileage. I'm just saying that if I get 51 mpg in the summer at recommended... I'm not going to get any better by just increasing PSI. I just want PSI in the equation. Please do not misunderstand the question. And sorry for not being clearer.

In other words, in your example above you got 62mpg at MAX. You estimate that you would have gotten ~55mpg at a lower psi. I'm asking can you just do the same test at recommended PSI (instead of at MAX). You are saying that you would have had a 7mpg increase with just tire pressure changes alone. I'm saying that I would like to see the data for that. I'm betting you can get closer to your 62mpg at recommended psi. Of course you would have to try to be as unbias as possible.

Thanks

 

i have been running my HCH-I with 40 PSI, on both my regular tires (which went bad on me late this summer) and my snow tires, which i have been running since then. i was hitting high 50s and an occasional 60MPG. i did a clinic with wayne gerdes about 6 weeks ago, and we pumped my tires to 60, though because of the dang cold up here in MN, they are at 55 right now. since then i have been regularly running mid 60s even in single digit temps and snow......actually, the first long run of 45 miles i did following the increased pressure was still in the warm weather and i pulled a 78MPG segment. i expect to be back in that range again next spring when i replace the snows and the weather warms up again.

i checked my mileage log and last year at this time, with the same tires and car, i was getting maybe mid 50s, frequently lower 50s.

 

Right now, I'm going through long term fuel map problems because I had a change from straight 87 octane to E10 with ethanol without knowing the station changed to it. My last tank was 41.3mpg which is the worst tank I've gotten since the last time this happen. I expect it will take three tanks to clear up the problem if I get straight gas from now on. The good part about all this is I've learned E10 is not all that bad if the fuel maps adjust to it like Debbie Katz's FEH did during our MPG Challenge.

There is no way I will lower my tires to 35psi for what I think would be a silly test for me because I know what it will do. When everything clears up with the fuel maps, I may compare what 60psi does to my mileage for the group as Wayne Gerdes has suggested to Laurie. There is no way this would lower my mileage, but it would be something to consider if it improved 2-3mpg on a tank with no other changes. If I get another 7mpg improvement, I'll make the change if it doesn't effect handling. BTW, Wayne was the one that convinced me to go to at least 50psi over a year ago. Now that I've seen the improvement this past year, I can take it up another step. I'm not recommending this to anyone and if I don't see much of a change right away, I'll lower them back to 50psi.

GaryG

 

What tires are using for snows? Blizzacks have a MAX of 35psi.

Whatever the tire, it sounds like you are exceeding the MAX printed tire pressure on the side wall of the tire. Something that I wouldn't recommend anybody doing. Also, are you doing FAS? If so, this is a technique that I don't use because it is not a supported feature and one could argue unsafe. In a court of law, if you were to get into an accident during a FAS, good luck talking your way out of it.

But saying all the above, it sounds like if you exceed MAX, there is a noticable difference in MPG attributed to pressure adjustment only.

 

Hi Gary,

Can you list what is the MAX psi of your tires? Are you exceeding MAX?

Also, what is the wear pattern of your tires now? Is it uneven now? With center wearing more than sides?

Thanks

 

My max sidewall is 44psi and yes I'm now at 6psi over. My wear pattern is great and wear has slowed down allot. These are steel belted tires and I see no center wear what so ever. The Escape has a problem with inside wear, but that wear has stopped since I increased the pressure. I've brought my FEH to Goodyear twice early on, and they said all Escapes have this problem. Other posters have also stated this is a common problem with their FEH.

BTW, I corner hard to maintain speed, and I see no evidence of outside tire wear.

Now that I've seen and talk to so many people that have increase their tire pressure much more than I do with only the harder ride being an issue, I don't feel as concerned anymore. After all, I bought the FEH because I wanted a SUV and good mileage. I will admit when I first started exceeding MAX sidewall, I did have the same concerns as you.

GaryG