[Rainsux]

We are about to take our first trip in our new 2020 HAH Touring. One of our hypermiling techniques in our G1 Insights is to overinflate the tires. It is hugely successful. I've driven thousands of miles at 55 lbs.

I've searched for this information here, but haven't found much. Has anybody experimented with this? If so, what is the optimum pressure? I understand that the ride will be rough, and I'm not worried about the high pressure.

Thanks for the help!

Sam

 

[Ziyang]

It’s probably not worth giving up the handling and traction safety for mpg.

 

[PetitFrereAccord]

I guess you will be the first. If you do the experiment and achieve great results, do well to come and tell us the optimum tire pressure.

As a rule, I usually have mine 2psi more than oem.

The door says 33psi. I put mine at 35psi. That is good enough for me. I was thinking of trying 36. But my rule is always to put 2 more than oem recommendation.

 

[jackpine]

Whatever, don't inflate to more than the max cold pressure shown on the tire's sidewall.

I'm actually puzzled about why you would want to try this. Yes, it saves a couple dollars in gas costs, but, it causes the center to the tire tread to wear more than it should, shortening the life of the very expensive tires in the process. And yes, the decreased tire footprint on the dry road will reduce your traction.

- Jack

 

[2Accordz]

We are about to take our first trip in our new 2020 HAH Touring. One of our hypermiling techniques in our G1 Insights is to overinflate the tires. It is hugely successful. I've driven thousands of miles at 55 lbs.

I've searched for this information here, but haven't found much. Has anybody experimented with this? If so, what is the optimum pressure? I understand that the ride will be rough, and I'm not worried about the high pressure.

Thanks for the help!

Sam

You're never supposed to exceed the maximum pressure that's imprinted on the sidewall of the tire.

I'd caution you on that...
Not only is it dangerous, but where your family is involved, you're going into some dicey legal territory as well, should there ever be an accident and the insurance adjuster found this info out.
It wouldn't bode well for you, I'd imagine.

 

[zroger73]

In today's litigious society, I'd be concerned about being found negligent by an attorney who discovered that I had willfully and knowingly exceeded the manufacturer's tire pressure specifications.

 

[rgoodman]

I can see, by the picture of your Insight, that you are obsessed with gas mileage; so use the max. pressure written on the tire if you aren't worried about it.

 

[Rainsux]

Well, I guess I've gotten all of the comments I'm going to. I don't have a baseline, so I was hoping that somebody was ahead of me. All I got was the expected "don't do this" responses.

You are a conservative group! Pretty much none of these responses are based on personal experience. Like "I put 45 lbs in my tires and immediately had four blowouts". No. They were all based on opinion and lack of knowledge. No actual facts. That's ok. Thanks to all of you for trying.

So I'm going to start at 50 lbs. If the ride is too harsh I'll go down. If it's ok I'll go up. When I've settled on a good ride comfort point I'll start experimenting with mileage.

When we get home and and it becomes my wife's DD again I'll air it back down. Maybe 40 or so. She put about 50K miles on her Insight CVT at 40 and never knew it. No tire issues on that car.

Sam

 

[BrianMcCartan]

Well, I guess I've gotten all of the comments I'm going to. I don't have a baseline, so I was hoping that somebody was ahead of me. All I got was the expected "don't do this" responses.

You are a conservative group! Pretty much none of these responses are based on personal experience. Like "I put 45 lbs in my tires and immediately had four blowouts". No. They were all based on opinion and lack of knowledge. No actual facts. That's ok. Thanks to all of you for trying.

So I'm going to start at 50 lbs. If the ride is too harsh I'll go down. If it's ok I'll go up. When I've settled on a good ride comfort point I'll start experimenting with mileage.

When we get home and and it becomes my wife's DD again I'll air it back down. Maybe 40 or so. She put about 50K miles on her Insight CVT at 40 and never knew it. No tire issues on that car.

Sam

Recommended is 33PSI. We run 36. I set them first weekend of each month at 36 on both of our HAH Tourings.
There are some valid comments here.
One thing I can say happened to me........Years ago on my GF's 2007 Civic I overinflated the tires to 40 instead of 32. She took a few 80 mile round trips in the hot July Chicago weather and the tires crowned. The center wore out early. Car started vibrating. Tires had to be replaced 10,000-15,000 miles earlier than should have been.
So since then, I only go 3-5 over. You have to keep in mind, if you are running 50PSI cold and you drive 80mpg on a 90-95 degree day, those tires will get to 60 PSI easy.
Be careful. Happy Hybriding. Safe travels.

 

[Hudouc]

You are a conservative group! Pretty much none of these responses are based on personal experience. Like "I put 45 lbs in my tires and immediately had four blowouts". No. They were all based on opinion and lack of knowledge. No actual facts. That's ok. Thanks to all of you for trying.

Actually, I'd say it's based on common sense. None of us really wants to find out what a bad experience would be.

What I can tell you from is experience is how different a car can act with even 5lbs of elevated tire pressure when driven at its limits. 5lbs greater in the front tires can increase understeer as there is less traction in the front, and 5lbs greater in the rear encourages oversteer due to less traction in the back. Greater pressure means less contact patch and less traction, its physics. Although this may seem far fetched for a lot of people, but it doesn't take much for you to end up in a situation where you are pushing the car to its limit (emergency braking, avoidance maneuver, etc.) When you are at the limit, you'll regret not allowing the car to perform at it's best based on your severely altered settings.

But I guess nothing we can you change your mind since ride comfort and fuel economy is clearly your number one goal. Luckily for you, factor of safety exists and you probably won't have a blow out.

 

[TX Accord]

I ran a set of tires at 47psi. Sidewall shows max press at 51psi. That set of tires wore out in the center before the edges wore down. On my car, I didn't notice any significant change in mpg to warrant doing that again. Now I run 35psi, rotate the tires every 15k, and try to get max life out of the tires.

 

[PhotoJim]

I haven't drunk hydrochloric acid. I don't need to in order to know that it's a bad idea.

The very thread title is "extreme tire pressure". "Extreme" is rarely good and never optimal.

Common sense dictates that higher pressure equals higher risk of blowouts.

I would bet that somewhere on the Internet is some research a person could read about the tradeoffs of lower versus higher tire pressure.

 

[Ziyang]

Common sense dictates that higher pressure equals higher risk of blowouts.

I agree with your reply except this sentence.

On the contrary, lower tire pressure equals higher risk of blowouts because 1) the side wall are more likely to be structurally damaged without sufficient pressure support and 2) low pressure leads to more deformation and thus heat accumulating at high speeds. High tire pressure is bad for traction and even tread wear.

 

[PhotoJim]

I agree with your reply except this sentence.

On the contrary, lower tire pressure equals higher risk of blowouts because 1) the side wall are more likely to be structurally damaged without sufficient pressure support and 2) low pressure leads to more deformation and thus heat accumulating at high speeds. High tire pressure is bad for traction and even tread wear.

True - low pressure increases risk.

I don't think that means that higher pressure doesn't increase risk, though. It depends on how well the tires are designed for high pressure. After all, pressure vessels like boilers fail when the pressure is too high, not when it is too low.

In any event, it seems a terribly unwise practice. It is already pretty easy to get years out of a set of tires.

 

[banjaboy]

God help you if you have any kind of accident that involves a braking/traction issue. Your insurance company will eat you alive. I think its irresponsible to consider this, much less post it on here. Beware would be my words to you

 

[InTotalAccord]

As a few people have noted, Michelin's spec for the maximum inflation of their Energy Saver tire (which was the OEM tire on my 2018 Hybrid Touring) is listed as 51 psi (I looked it up on www.tirerack.com, in the specs table for that tire, but I believe it is molded right into the tire sidewall.)

Interestingly, the max inflation rating for Michelin Defender T+H tires in the same size 225/50-17 (another pretty popular "standard touring all-season" tire) is only 44 lbs.

Max. inflation specs for tires used to be mostly in the low-to-medium 40's (psi), but recently it has become more common to see a rating of 51 psi, since more and more people are interested in pumping their tires up more, for greater fuel economy.

I wouldn't go beyond the manufacturer's max rating, and in fact would verify it with tires "hot", after driving around a while. And in actual practice, while I sometimes pump my tires up a few psi over the owner's manual recommendation, I don't ever get close to the max rating, as I think the result will be harsh ride, overly "skittish" steering feel, reduced grip (especially in wet or snowy conditions), and excessive wear in the center of the tread.

To each his (or her) own, but the manufacturer's maximum rating is at least a "fact", of some sort....

 

[qman]

If this is one of your "techniques", why are you asking? Its not like tires have been reinvented on your new car.

FWIW tires don't blow til about 190 psi.

 

[Rainsux]

Well, my first test was unsuccessful. The wedding we were going to was cancelled (Covid), so I lost about 2,500 miles of testing. I wound up with an 800 mile trip, 400 each way.

The first leg was at about 32-33 PSI, and I got 48.3 MPG. Then I aired the tires up to 50 lbs. The mileage on the return trip was......Wait for it.......48.3. I tried to be consistent, but surely there were differences in elevation, wind, etc. The next time I take a trip the pressure will be higher.

I noticed NO harshness with the higher pressure, and the car actually felt a little better. When I aired them back down it felt a little squishy.

Stay tuned!

Sam

If this is one of your "techniques", why are you asking? Its not like tires have been reinvented on your new car.

FWIW tires don't blow til about 190 psi.

I explained this in my first post. I was trying to avoid reinventing the wheel. If somebody had already done this it would have given me a starting point. There is a lot of information on the G1 forum, but nothing here. Maybe this thread will spark some interest in others.

Sam

 

[rgoodman]

With my driving, I was getting about 40mpg at 36psi, 42mpg at 38psi, and 44mpg at 40psi.

 

[PhotoJim]

So now the question is how much overinflation will affect tire life and braking.