How much do you inflate your tires...tire spec or vehicle spec?

[Piratemud]

I use vehicle spec. The point is to have a flat contact patch for optimum grip. This reflects in the tyre wear - my tyres wear evenly.

 

The vehicle engineers are smarter than you, their recommendations are 100% solid.

[The Evil Overlord]

I use vehicle spec. The point is to have a flat contact patch for optimum grip. This reflects in the tyre wear - my tyres wear evenly.

The vehicle engineers are smarter than you, their recommendations are 100% solid.

That'll explain the the melting tyres on explorers and mavericks that lead to a couple of fatalities, as vehicle spec inflation was lower than tyre manufacturer recommendation in those cases, and was pointed out by the user above you.

I remember the story on the news, there was even a watchdod episode about ford's attempt to shift the blame, and attemting to cover it up etc...

[+LogicalApex MVC]

Though my first instinct was to go with the vehicle's PSI recommendation, I think that going by the tires' stated PSI is just as good, if not better. Here's why:

 

1 - Though this is just a theory, it seems vehicle manufacturers would recommend a lower PSI rating so that traction is increased and safety specs improved (such as those advertised in commercials like shortest stopping distance, best handing, etc...). Though perhaps better to show off specs and in bad weather, it's probably wise to go higher for everyday, average-use purposes.

2 - Auto manufacturers might assume that a tire is inflated before being mounted. Thousands of pounds of car is sure to increase the pressure, so maybe the auto's recommended pressure is just in case the average consumer doesn't;t take that into consideration and max-fills the tire before mounting.

3 - Are the tires factory-originals? Even if the tire size and ratings are the same the recommended PSI can vary greatly from brand to brand and make to make. In this case the auto's PSI recommendations are likely irrelevant, unless you get the exact matching tire models.

4 - My car "disapproved" of its own door-mounted PSI.    The TPMS light kept coming on in my 2006 Mazda Tribute (a.k.a. Ford Escape, Mercury Mariner). I had all tires inflated to and slightly above the recommendation of 30 PSI, but still the light was on and I could tell there was a lot of excess drag when turning. So I switched to the tires' specs of 44 PSI, and now the TPMS is off, no more high-drag feeling from the tires, and at least 2 MPG gained!!! No bulging or excess wear points to be seen. (similar scenario with my Chevy Tracker too)

 

So based purely on what I've experienced, go with the tires' ratings. As long as the PSI is taken with the load of the vehicle already being applied there should be no problem.

 

By the tire? Why? That makes very little sense. The people who designed the car should know far better than the guy who designed a tire for a whole host of cars... My tire has a max PSI of something like 60+ PSI, but the car recommends 32PSI. You're essentially asking for almost double what the manufacturer recommends which makes no sense.

 

My car's Continental Tires are OE equipment on a crap ton of cars...

 

Also, you can adjust the TPMS reference point... Someone set your TPMS to the wrong reference values. You should reset it to the correct pressures to ensure you're safety on the road.

 

Never follow the door, once the Tires have been replaced.  You should do 15% less then max.   

 

Following the door recommendation is why FORD and Firestone had issues, the tires max was 44, and the trucks door said 25-27, way to little to allow the tire to cool.  

 

This is not the only example, but the car door tag was for the original spec'ed tires (not necessarily the ones that ship with the car 

 

You're also suggesting ignoring the recommendation of the car manufacturer without anything other than one case where the OE failed to list correct pressures? Even though overfilled tires lead to uneven tread-wear at a minimum and a blowout at its worst.

 

No one in the industry recommends this...

 

Tire manufacturers don't recommend it:

 

 

Do not use the number on your tire

[The Evil Overlord]

By the tire? Why? That makes very little sense. The people who designed the car should know far better than the guy who designed a tire for a whole host of cars... My tire has a max PSI of something like 60+ PSI, but the car recommends 32PSI. You're essentially asking for almost double what the manufacturer recommends which makes no sense.

 

My car's Continental Tires are OE equipment on a crap ton of cars...

 

Also, you can adjust the TPMS reference point... Someone set your TPMS to the wrong reference values. You should reset it to the correct pressures to ensure you're safety on the road.

 

 

You're also suggesting ignoring the recommendation of the car manufacturer without anything other than one case where the OE failed to list correct pressures? Even though overfilled tires lead to uneven tread-wear at a minimum and a blowout at its worst.

 

No one in the industry recommends this...

 

Tire manufacturers don't recommend it:

 

 

Source: Michelin Tires

 

Tire sellers don't:

 

 

Source: Tire Rack

 

OEMs don't:

 

 

Source: Toyota

 

The government safety regulators don't:

 

 

Source: National Highway Safety Administration

 

I'd think all of these engineers would have a pretty good handle on giving us a solid recommendation on where to look. Stop putting yourself and others at risk on the road.

 

 

 

See above...

I used to work at Goodyear Wolverhampton, and disagree.

Going back to the ford vs Firestone debacle, ford even admitted using lower tyre pressure, to lower the centre of gravity of their mavericks and explorers, they made a huge fuss about it also, first they blamed the deceased drivers for dangerous driving, then they blamed Firestone for poorly made tyres, if it wasn't for the fact that Nissan, Toyota, and Chevy were using the same tyre without ever having an incident, they might have gotten away with it.

The watchdog episode I'm thinking about (not sure if it was aired in the States) was a full on investigation, and found that ford was responsible for the 2 deaths because of their lower tyre pressure recommendation.

[sc302 Veteran]

However the manufacturer specs takes into consideration load where the tire manufacturer tells you the maximum tire pressure the tire can safely hold without failure/blow out.  Over inflation can lead to tire wear.  perhaps over or under inflating to the point of noticing tire wear would do you some good so you know the limit of where the tire can accept at the particular load the vehicle has, you may ruin the tire doing this but I guess that would be better so that you know where too much or too little is for the tire.  5psi up or down isn't going to make too much of difference 20 psi is a different story.  when you get a center strip of lower tread that is too much pressure, when you have strips along each side of the tire that is too little. 

 

how to read your tires: http://www.procarcare.com/includes/content/resourcecenter/encyclopedia/ch25/25readtirewear.html

 

how over inflation affects tire wear: http://auto.howstuffworks.com/over-inflation-affect-tire-wear.htm

 

If you did work at a tire place you would know this.  As a automotive enthusiast and a graduate of an college automotive repair program (albeit before the ford issue...although I did own an explorer and did not have the issue that was reported with the same firestone tires that were in question), I have been taught this.

[The Evil Overlord]

However the manufacturer specs takes into consideration load where the tire manufacturer tells you the maximum tire pressure the tire can safely hold without failure/blow out. Over inflation can lead to tire wear. perhaps over or under inflating to the point of noticing tire wear would do you some good so you know the limit of where the tire can accept at the particular load the vehicle has, you may ruin the tire doing this but I guess that would be better so that you know where too much or too little is for the tire. 5psi up or down isn't going to make too much of difference 20 psi is a different story. when you get a center strip of lower tread that is too much pressure, when you have strips along each side of the tire that is too little.

how to read your tires: http://www.procarcare.com/includes/content/resourcecenter/encyclopedia/ch25/25readtirewear.html

how over inflation affects tire wear: http://auto.howstuffworks.com/over-inflation-affect-tire-wear.htm

If you did work at a tire place you would know this. As a automotive enthusiast and a graduate of an college automotive repair program (albeit before the ford issue...although I did own an explorer and did not have the issue that was reported with the same firestone tires that were in question), I have been taught this.

Was this meant for me? If so, yes I am aware and do know, I haven't forgotten it all in my old age yet

To answer your points.

I am aware of how tyres behave under incorrect tyre pressures, and how weather can dramatically affect poorly inflated tyres. I'll admit I was purely focussed on the ford issue.

Now I work as a truck driver, and often see what happens when an underinflated tyre blows out on big rig trailers, not to mention the noise they make when they do blow out.

Vehicle manufacturer recommendations I rarely believe, unless they align with the recommendation of the tyre manufacturer..

I can offer an example (you'll have to excuse this part, as I did not take a picture for reference) Mercedes on their converted sprinter vans (converted to armoured cash carriers and ambulances) give a recommendation on each arch, for the preferred inflation of tyres, they usually recommend uniroyals when it comes to light commercial and heavy goods vehicles, on a few of these ambulances and armored cars, I've seen tyre pressure recommendations of up to 76 psi (if I remember to snap a pic, I'll happily post it) uniroyal agree with this, I'll always get a second opinion where possible until I'm suitably comfortable. That's just me, I've seen a family wiped out when their car was flattened by an out of control coach, which, after a blowout, rolled onto it, back in the 80's (such images never really leave a person, and change the way a person absorbs advice)

And now for the smartass in me, you forgot to mention how to tell if a vehicle is negotiating roundabouts regularly at excessive speed, the outer edge of the (front left or right, depending on which side of the road one happens to drive on) of the tyre

[sc302 Veteran]

well hopefully if you are negotiating "roundabouts" at excessive speed, you aren't going to complain about uneven tread wear or premature wear . 

 

Those heavy vehicles probably have an F load tire with a 95 psi rating...not dealing with a passenger tire at 50-65 psi rating.  Is the vehicle manufacturer the final manufacturer or is the ambulance/armored car manufacturer the final manufacturer where you should listen to the pressure rating on the tires.

[The Evil Overlord]

well hopefully if you are negotiating "roundabouts" at excessive speed, you aren't going to complain about uneven tread wear or premature wear .

Those heavy vehicles probably have an F load tire with a 95 psi rating...not dealing with a passenger tire at 50-65 psi rating. Is the vehicle manufacturer the final manufacturer or is the ambulance/armored car manufacturer the final manufacturer where you should listen to the pressure rating on the tires.

The refitter, they usually buy the vehicles in bulk, and refit/rebody, the cab exterior usually, mostly left alone in the instance of ambulances, barring the fitting of lights and strobes. (Armoured cars, of course, needing a lot more reworking of said cab) So I will say, the refitter is the final manufacturer.

<off topic>I apologise for my rant</off topic>

[Hrlymn]

Most of you are very wrong! You only go by the vehicle sticker if you have the EXACT tire on the vehicle that it rolls off the line with. The sticker in the door doesn't know what tire you or a previous owner has put on the vehicle. Use the sticker on the vehicle to buy the type of tires rated and recommended for that particular vehicle. Other than that, inflate to 5-7psi under the max pressure it says on the tire itself. I have a 2012 XB with lowpro toyos and the max press on the tire says 50psi so no, that is not insanely high. It all depends on the type, size, rating and brand of tire choice. It's not rocket science, always read from your actual tire spec. 

[Jim K Global Moderator]

Please do not resurrect old threads. Last response has been well over 2 years.

 

...and welcome to Neowin!