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I have a question, How dangerous is it to run with tire to the maximum pressure stated on the tire and has anyone experienced a tire blowing out because of the over inflation of the tires?

I have a 2000 Honda CR-V 2.0 L 4WD automatic 4 speed - the manufacture recommends 26 PSI but the maximum pressure on the tires state 35 PSI.

I currently run them at 30 PSI because it looks like they are to low.

http://www.cleanmpg.com/garage/images/his2336.png

Please don't take this as a recommendation of any kind but, I have been running 80+psi in my '07 Prius for nearly a year; they have never been below 60psi since the day I bought it. The stock Integrity tires have a max sidewall psi of 44. The car has 23K+ miles on the odometer. Also, welcome to CleanMPG.

Hi srullens--

A 26 PSI recommendation is why the Firestone tires would fail on Ford Explorers. Underinflation = too much heat and friction = boom. If anything the 35 PSI listed on the sidewall should be the bare minimum safe pressure for your vehicle. I can't recommend this either but I have had my tires over 50 PSI for a long time, and now over 60 recently with no problems at all.

There's a thread somewhere here where some of the regulars posted shots of their tire's treads showing even wear even at higher pressures. I've gone to 50# now.

The tire manufacture says max for my tires is 44.
If the manufacture feels good saying 44 then I am good with it.

I have NO proof but…
I have a feeling there is a safety buffer above the listed max.
If they listed something and tires were blowing out they
would get sued. Tire manufactures are not stupid, they don’t
want to get sued, so there going to keep the max low enough
so they shouldn’t have any issues.

Thanks for the info I'll try it a 35psi, When I get the new tires which are going to be Pirelli Scorpion ATR On-/Off-Road All-Terrain light truck tires are rated at 44 psi.

http://www.cleanmpg.com/garage/images/his2336.png

I have a question, How dangerous is it to run with tire to the maximum pressure stated on the tire ...

I have a 2000 Honda CR-V 2.0 L 4WD automatic 4 speed - the manufacture recommends 26 PSI but the maximum pressure on the tires state 35 PSI. ...

My Accord is also rated for 26 PSI, but the very first winter it hydroplaned too easily compared to previous cars, and this seemed dangerous. For the next 21 years, I ran it at 32 PSI, with better wet weather results and no problems. When joining this forum I pumped it a bit higher to the sidewall max, but don't have enough experience there to provide any useful feedback.

When boosting my Subaru to its sidewall max, I read the tire sidewall statement more closely -- it clearly indicates that the maximum load rating of the tire applies *only* when inflated to the maximum pressure. That means when the pressure is lower, the tire cannot safely carry its full rated load. Personally, I want to maximize this safety margin.

I have a question, How dangerous is it to run with tire to the maximum pressure stated on the tire and has anyone experienced a tire blowing out because of the over inflation of the tires?

I have a 2000 Honda CR-V 2.0 L 4WD automatic 4 speed - the manufacture recommends 26 PSI but the maximum pressure on the tires state 35 PSI.

I currently run them at 30 PSI because it looks like they are to low.


26 psi is crazy. My civic is built on the same platform as your CR-V, but yours is bigger and heavier. My manual calls for 32 psi.

My last set of tires, pre-hypermiling, I ran at 35 psi the whole time. They wore out on the edges - a clear sign of UNDERinflation.

Go ahead and pump them up to the max on the sidewall.

Well 7:00 am this morning I inflated all tires to maximum pressure of 35 PSI. I hope to see a mileage increase too.
I also found this information at this page http://www.sportcompactcarweb.com/tech/0208scc_tire_pressure_guide/index.html
The rule is:

(Vehicle Weight in lb/100) + 2 psi at heavier end + 2 psi all around if suspension and alignment are stock.

Example: Stock 911, 3,000 lb.
(3000/100) = 30 psi
Add 2 psi all around = 32 psi
Add 2 psi to heavy end = 34 psi at rear
With modified suspension, the result is 30 psi front, 32 psi rear.

http://www.cleanmpg.com/garage/images/his2336.png

There is a 6 times safety factor built into the sidewall max rating. Here is a good source from an actual tire engineer that worked in the failure field.

Barry's Tire Tech (http://www.geocities.com/barrystiretech/rrandfe.html)

32 or 36 psi is low on a CRV.

My Accord is also rated for 26 PSI, but the very first winter it hydroplaned too easily compared to previous cars, and this seemed dangerous. For the next 21 years, I ran it at 32 PSI, with better wet weather results and no problems. When joining this forum I pumped it a bit higher to the sidewall max, but don't have enough experience there to provide any useful feedback.

When boosting my Subaru to its sidewall max, I read the tire sidewall statement more closely -- it clearly indicates that the maximum load rating of the tire applies *only* when inflated to the maximum pressure. That means when the pressure is lower, the tire cannot safely carry its full rated load. Personally, I want to maximize this safety margin.

I remember a formula a cop told me a few years back that went something like five or six time the square root of the tire pressure was the speed you could hydroplane. I looked around the web and did not find the same factor. The two formulas that showed up were nine times the square root of the tire pressure and 10.25 times the square root of the tire pressure. Of course they all mentioned other variables can influce the speed at which you could hydroplane, but that was the key formula.

A few good links on the subject.

for airplane tires and used the nine as the multiplier (http://wiki.answers.com/Q/How_can_you_determine_at_what_speed_a_car_will_hydroplane)

From a fireengine journal it looks like. (http://www.fireengineering-digital.com/fireengineering/200702/?pg=52) They used the 10.25 multiplier. They also did not like the cutoff on tread depth on when you should replace your tires. From experience over the years I have to agree with them on that. I always replace my tires a bit early.

And lastly from tirerak.com (http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=3) This may be the best discussion with lots of details and some images of the tread on the road surface at various tire pressures.

I'm a bit conservative. My tires are right at the sidewall pressure (44psi) and have had no problems.

Hi Paul:

___Try it? We recommend it :D

___Not only better FE but far safer over the short and longer terms too!

___Good Luck

___Wayne

I know good tire pressure commonly recomended around here _ and rightly so. I was wondering if anyone has attempted to quantify the benefit of adding more pressure and what's stated on the sidewall.

Currently my tires are at max sidewall pressure (51psi). I wonder how much improvement I might see if I add say 25pct more pressure, 50pct more, 100pct more.

I also suspect it might be dangerous to inflate them to say 100-150 psi. ( In the event that one should pop due to say an unnoticed defect or whatever )

this was posted by someone else, it has some great info on tire PSI.
http://www.geocities.com/barrystiretech/rrandfe.html

From what I have been reading. The gains are less and less as the PSI goes up.
Your still getting gains from more and more PSI, but those gains are smaller
and smaller.

... hydroplane. ... The two formulas that showed up were nine times the square root of the tire pressure and 10.25 times the square root of the tire pressure. ...
A few good links on the subject.

for airplane tires and used the nine as the multiplier (http://wiki.answers.com/Q/How_can_you_determine_at_what_speed_a_car_will_hydroplane)
...
They also did not like the cutoff on tread depth on when you should replace your tires. From experience over the years I have to agree with them on that. I always replace my tires a bit early. ...

Notice that the 9X factor is for aviation, using *nautical* miles per hour. Converted to our common road miles, this factor becomes 10.36X, essentially the same as the 10.25X multiplier in the other link.

As for minimum tread depth, I also agree, replacing mine when wet braking traction becomes unsatisfactory. This always happens well before minimum tread, but folks who drive in drier climates are likely to get more tire life than I do.

I've been running my firestone f-590 tires at a sidewall rating of 44psi for 3 years now with no adverse effects. Recently went up to 50psi and still no problem. Treadwear is even and currently at about 3mm depth after 110,000km. No noticeable loss in traction, wet or dry and they roll like a good thing!

ollie

One thing to remember is not to confuse the car manufacturer recommendation, typically found in the drivers door jamb, and the tire manufacturers maximum, listed on the sidewall of the tire.

A 195 series tire or narrower running lots of pressure tends to wear the centers less than wider tires typically center wear from over inflation, in my limited experience anyway.

Another thing to remember is that handling and cornering at the limit will be affected by tire pressure. My Z28 gets ~1 mpg better with the tires pumped up, but the upper limits of corner speed (my favorite thing to do in a car) are handicapped by running higher pressure. I justify it in my mind by believing the higher corner speeds are helping conserve fuel. :)

981 LE:

___I don’t think anyone has seen center wear at higher pressures and that includes any size tire to date? The MDX’s and Ranger’s treads are even all the way across let alone will last twice the period of those running at placard and below.

___Good Luck

___Wayne

There is a 6 times safety factor built into the sidewall max rating. Here is a good source from an actual tire engineer that worked in the failure field.

Barry's Tire Tech (http://www.geocities.com/barrystiretech/rrandfe.html)

32 or 36 psi is low on a CRV.


How is it we know the safety factor is 6?

Hi Capri:

___I can only speak of Bridgestone and Michelin at 5 + X's max sidewall from the engineers I speak with at the Auto Show Press Events.

___Good Luck

___Wayne

Another thing to remember is that handling and cornering at the limit will be affected by tire pressure. My Z28 gets ~1 mpg better with the tires pumped up, but the upper limits of corner speed (my favorite thing to do in a car) are handicapped by running higher pressure. I justify it in my mind by believing the higher corner speeds are helping conserve fuel. :)

Hm, I've experienced just the opposite, handling and cornering abilities on my Corolla went way up once I pumped up the tires. Might be the difference in a sports car suspension such as your Z versus the Corolla' soft ride suspension.

Hm, I've experienced just the opposite, handling and cornering abilities on my Corolla went way up once I pumped up the tires. Might be the difference in a sports car suspension such as your Z versus the Corolla' soft ride suspension.

I was looking over some of the "AAA Responce"
http://www.cleanmpg.com/cmps_index.php?page=AAA

there is a link in there that states cops use the Max side wall not manufacutre.
they are saying the same thing - higher PSI gives them better performance.

http://www.officer.com/web/online/Editorial-and-Features/Driving-Under-Pressure/19$27281

it's a good artical.

phys :D

Psych :0

I inflate to 62 on a 35 rated tire. I have no wear issues over 2000 miles, and it handles better wet and dry more than I have ever experienced before. They are wearing longer as I can tell compared to my lower pressures in the past. I believe Wayne has high pressure in his tires and has driven over 100k on them, if I remember correctly...

Thank everyone,
I am up to 35 PSI, I need new tires. They are showing signs of cracking. Most likely will Get On/Off Road tires Pirelli Scorpion ATR. Need a tire that's good in snow, sand, mud and the Hwy.

I have suffered a side blowout, but not due to pressure. Used to work in Little Rock, and they have a number of curbs thats are tall, sharp, and close to the road (small gutters). I rubbed against those several times & caused tire damage. In one case, I did it before a long road trip. On the intersate I noticed a sound. Pulled over & found a low pressure tire. I had a portable inflator & started pumping it up. I large blister formed where the scrape was worst. I started to drive the car to the top of the ramp so I'd have a level surface to change the tire, but the tire blew so I ended up changing it on the offramp (low traffic).

Despite that experience, I have no problem running at max sidewall. I'm confident in the tire manufactures recomendations & know the tire has a safety margin built in.

981 LE:

___I don’t think anyone has seen center wear at higher pressures and that includes any size tire to date? The MDX’s and Ranger’s treads are even all the way across let alone will last twice the period of those running at placard and below.

___Good Luck

___Wayne


Actually...

My F250 diesel pickup recommends 80 PSI for the rears and 55 psi for the fronts. If I run like this with the truck unloaded, I get bad center wear on the rears. So...I go 55 all around for even tire wear. BUT I plan on using 80 psi all around anyway for hypermiling the beast because the MPG gained and money saved will more than buy a few sets of tires!

[disclaimer - follow recommended tire pressure from the manufacturer as stated on the drivers door placard and ignore the following statement on this post:]

The way hypermilers drive - low speed, low performance driving, it should be relatively safe to overinflate tires past recommended pressures if done reasonably. The hazards are blowing a tire. Tires heat up when driving, so your tire pressure will go up. I'm at the belief that when you inflate tires, you should inflate them hot which will be the pressure that they will be running on most of the time. I have my 35psi max sidewall tires at 40 and am considering increasing them higher. So far, I haven't heard of anyone getting hurt from overinflating tires.

Please use caution when inflating tires - we don't want anyone getting hurt out there!

Hi 99Metro:

___Let us go over a few items…

___I cannot speak for an F250 and the 80 psi rated tires but can of passenger car and truck tires. Max sidewall is also not over-inflated as it is on the tire itself. Risk of blowout is none vs. under inflation where the risk is magnified. Ford Explorer is/was a death trap due to the under inflation problem. Finally, running door placard today, you are underinflated tomorrow and it gets worse as days turn to weeks and weeks turn to months. How do you think 80% of the tires on the road got to an underinflated condition anyway? Door placard to begin with is how.

___As for performance driving, I can’t say all that much other than if you have entered into sweepers as some here do, your F250 would be on its roof in the ditch more than just a few times ;)

___Good Luck

___Wayne

Just curious -

If simply increasing tire pressure will yeild an automatic gain in say several mpg, why wouldn't all manufacturers jump all over this? If I'm manufacturing car x that gets say 33/37mph and say doubling the pressure brings it to say 36/40mpg without significant safety risk ... that would be a no brainer... free competitive mpg improvement without having to add to the expense of the vehicle...

( there must be a good reason... )


( i'm not questioning the practice of doing this.. in fact i've just upped my tires to 120% sidewall )

Just curious -

If simply increasing tire pressure will yeild an automatic gain in say several mpg, why wouldn't all manufacturers jump all over this? If I'm manufacturing car x that gets say 33/37mph and say doubling the pressure brings it to say 36/40mpg without significant safety risk ... that would be a no brainer... free competitive mpg improvement without having to add to the expense of the vehicle...

( there must be a good reason... )


Comfort

Car makers could do a lot of things to increase mileage. They do the thinks that they feel won’t hurt sales.
AC is example of a comfort items added to cars. It can only hurt mileage.

Higher tire pressure hurts ride comfort.

Make sure to check that psi every now and then. I got my new 44 psi firestones a couple of months ago, and the first thing i did was get em up to 50, just in case I lose some air on the road, so i will not be underinflated!
i decided to check my tires yesterday and they were all underinflated by 6 psi! all of them were 40! So i drove the first 120 miles of my fall fe run with underinflated tires!:mad::rolleyes:
I went in and got my hand pump for a bicycle, and pumped em up to 55! it worked good, plus it gave me a free workout! ;)

I upped pressure to 70 psi and will try it out. 35 is sidewall max ...anyone see any problem with that? They have been in the low 60's so far with no issues and great handling so far.

I have tires with max sidewall of 51. How much higher can they safely be inflated?

What usually happens to old tires when you get a new set? Do they recycle by doing a retread, like on semis, or are they usually shredded and reused that way?

I ask, because if they are going to be shredded, I might be willing to put the pressure to one and see what it takes to blow when I next have to swap out tires. Ideally I want to do that as a hydrostatic test to reduce risk, but if I can get a cheap rim, a long enough pressure hose (with a high enough rating), and a large field, I'd do it with air pressure only...much more dramatic.

I'd prefer someone like Mythbuster do it, so everyone could see what the effects are.

a long enough pressure hose

I bet!:eek::eek:

I'd prefer someone like Mythbuster do it, so everyone could see what the effects are.

get someone to video it, then put it on youtube :)

What usually happens to old tires when you get a new set? Do they recycle by doing a retread, like on semis, or are they usually shredded and reused that way?

I ask, because if they are going to be shredded, I might be willing to put the pressure to one and see what it takes to blow when I next have to swap out tires. Ideally I want to do that as a hydrostatic test to reduce risk, but if I can get a cheap rim, a long enough pressure hose (with a high enough rating), and a large field, I'd do it with air pressure only...much more dramatic.

I'd prefer someone like Mythbuster do it, so everyone could see what the effects are.

As a general rule, they do not retread passenger car tires.

May I suggest you pick a 6 year old tire, with a single ply polyester sidewall and a 2 ply steel / 1 ply polyester tread. Check for punctures and repairs (you don't want those!).

You'll want to record the size, manufacturer, trade name as well as the DOT code, the max load and max pressure listed on the sidewall.

You'll need a compressor and a line that is capable of handling 200 psi. You'll want to add pressure slowly - something on the order of 30 psi a minute. Be sure to record the max pressure achieved. BTW. this may take as long as 10 minutes.

Be careful how you position the tire. Laying it down on the ground could launch the tire into the air. I've heard of vaues that exceed 100 feet. So stand the tire up in a secure fixture if you can. Leaning against the wall is also not a good idea.

You'll also want to replace the valve with a metal one. Rubber ones will probably be pushed out.

After the test, survey the results. Did the tire burst at the bead, the sidewall or the tread?

If it was the bead, was it the rim that yielded? Check the rim for damage, bends, etc. And don't forget to check the valve.

I was with a friend that over inflated a bicycle tire. I have changed a lot of bike tires, and I have over inflate a lot of them and never blown one out. So I am guessing he had the tire well over 150 PSI when it blew. It scared the ship out of us when it blew.

I have seen airplane (dc9) tires after they blew out.

I had a front tire blow out on me. (from low PCI not high) that one put a hole in the tire you could fit your fist in. there was 4 of us in the car. The tire blew on the inside wall, throwing the chunk of rubber against the car. It felt like someone has shot the car, we all looked around to see of someone was point a gun at us.

I seen cages at tire shops for mounting and inflating tires. The cage is there to help keep anyone from getting hurt or killed if the tire was to burst.

From my experience’s I would not want to be with in 100 yards of someone trying to blow out a tire from over pressure

I disagree about the metal valves Most people use rubber valves and we want to know where the failure occurs. A failed valve due to excess pressure is just as important to know about as the sidewall or rim.