Tire PSI...

[johnl]

and branches of the uk, I.E Aus.

I know that Kevin Rudd (Australian Prime Minister for those less well informed...) is currently enjoying White House hospitality, but statements like that could be a cause for war...

[reaction360]

tire recommendations are kinda iffy and like before stated very controversial. I've been involved in threads on other sites too and people do get pretty defensive. Vehicle mfg. specs are fine i guess if you're running the exact oem tire. thing is aftermarket tires alll have different ratings and designs.

For example I looked up one tire in our computer at work and it says Max tire psi is 44psi......but thats at a load of 2300lbs on that one tire. so 4 of those max out on a car would equal the ability to load up to 9200lbs. I highly doubt any cb7 loaded will ever weigh 9200lbs. So 44psi would be overkill.

So as for me, at our tire store, we usually air up most passenger cars to around 35psi, some at 40psi depending on the size of the tire/wheel. now newer vehicles with tpms sensors require a specific psi on the front or rear tire according to the placcard sticker in the door jam.

I would just say watch your tire wear, it'll usually help tell you if you're running too much or too little air pressure.(as long as your alignment is good)


-Zol

[hpaccord91]

thats not a good idea to put at tire max MAX psi you hit a bump the wrong way and kiss your tire good bye, i put all my hondas at 32 psi on my 91 accord i got just about little over 450 miles to full tank and my 2000 accord i get 500 miles to full tank , set them at 32 thats what it says on the door, and plus its a nicer comfortable ride your car isnt slamming everywhere and it doesnt feel like your hitting a brick wall when you hit a bump

[johnl]

thats not a good idea to put at tire max MAX psi you hit a bump the wrong way and kiss your tire good bye,

What evidence do you have to suggest that tyres become more prone to failure at / near the tyre manufacturer's recommended max psi? It's a myth (this might be a job for Adam and Jamie...?).

Do you really think that the tyre manufacturers are going to expose themselves to the very real risk of litigation by suggesting pressures that are dangerously high?

set them at 32 thats what it says on the door,

The tyre placard on my CB7 stipulates 270kpa (= 39psi) fo "consistant high speed". Lower pressures for lower speed use are stipulated only because it reduces ride harshness.

and plus its a nicer comfortable ride your car isnt slamming everywhere and it doesnt feel like your hitting a brick wall when you hit a bump

I suspect you are thinking that higher psi causes a much greater increase in harshness than it actually does...

Of course if higher pressure makes the ride too harsh for a particular person's taste than it perfectly OK for them to lessen the pressure (within reason).

[starchland]

I just have to wonder if your running your tires at 40psi what they are at when heated...which is probably exceeding the max tire pressure.

[93F22A6]

Tire manufactures take that into account. Plus I really dobt your gonna get your tires hot enough to build enough pressure to blow it. Plus over time your tires loose air, so just because you set then at XXpsi doesn't mean they are still at that psi. I know from being at the race track you can build 10psi in tire in only a few mins(15 min practice), but thats on a late model stock race car with Hoosier tires on it. Almost every tire is different, to me I set tire psi according to the type of tire and the type of driving. For example my CB, I run an average of 45-50 psi(+ or - a few psi). But I drive a lot of interstate, high speeds . Plus I like to fell the road to. Now if you just do some city driving with stock type tires then 35psi is just fine. What ever the tire says it needs it what you should put in it. The psi recomedation are on the tire for a reason so go by them.

[johnl]

I just have to wonder if your running your tires at 40psi what they are at when heated...which is probably exceeding the max tire pressure.

My car / my tyres at the reasonably high psi I run, on a warm to hot day after an extended period at 100 / 110kmh, the pressure increase from cold is about 4 or 5psi. Note that this still places my hot psi at / near the tyre manufacturer's recommended max (44psi), but if the tyre felt better and wear was OK at 44psi cold then I'd be happy to run them at that psi (and most likely end up with about 48psi hot).

I'm sure this will vary somewhat with different tyres and different weight cars etc, but as base (cold) psi increases the degree to which pressure rises reduces (arbitrary e.g. - in X conditions the pressure rise at say 20 base psi may be something like twice what it might be at say 40 base psi). This is because less inflation = higher tyre running temperature, and it's the temp increase that causes the pressure increase (and what typically causes nearly all catastrophic tyre failures).

As already said above, the tyre manufacturer recommendations are cold inflation pressures. They know the psi will increase when warm, and take this into account. People get worried about the tyre bursting like a balloon at higher psi, but in reality the burst pressure of any road car tyre is way way higher than the max psi marked on the sidewall.

The tyre maker's sidewall psi is a fairly arbitrary number (and neccesarily conservative), arrived at through a legislated formula that takes into account other parameters of the tyre's construction. Some tyres may even work better at some psi somewhat above their recommended max, but I feel a line must be drawn somewhere and personally won't go higher than the sidewall max.

[wed3k]

I just have to wonder if your running your tires at 40psi what they are at when heated...which is probably exceeding the max tire pressure.

thats what drag racing is all about...wondering what the tire pressure is after exiting the water box.

[JaK FRoSTWhiTE]

So, I filled my tires the other day to 40psi out of 44 (max). My friend was saying that that might be a bad idea. He was saying that tire PSI recommendation is in the owners manual. Any truth to this? What PSI should they be filled at?

Just pump up your tires to the recommend factory specs on the door jamb.

[johnl]

thats what drag racing is all about...wondering what the tire pressure is after exiting the water box.

Probably about 5 rather than 4psi...

[johnl]

Just pump up your tires to the recommend factory specs on the door jamb.

That's always an option, though it won't be anywhere near ideal for every tyre, vehicle use / set up, driver...

Keeping in mind that we are talking about a 'family' sedan here, the car makers recommended pressures assume a very limited range of parameters within which they envision the car being used. They don't take into account other than stock tyres, suspension mods, or more 'sporting' driving style and driver preferences / ability.

[carlosamador16]

So, I filled my tires the other day to 40psi out of 44 (max). My friend was saying that that might be a bad idea. He was saying that tire PSI recommendation is in the owners manual. Any truth to this? What PSI should they be filled at?

To answer your question, you have to look-up the specs for that particular tire.

[slammed4thgen]

Just pump up your tires to the recommend factory specs on the door jamb.

spoken like a true honda worker

now i dont know what you do for a living...but im willing to bet you are a tech for a dealer.

[areannecl]

I have capitol negotiators and the max is 51 psi...is it okay to run it at 40 psi then?

[ikayto]

I have a few friends that work for Yokohama corporate and I was letting air out of my tires because I recently pumped them up to 35psi for a long trip to get better mpg. I didnt like the harsher ride of adding 5 more psi.

He said to not fill in my tires or measure my tire psi after the tires have been driven on for a while because air expands and I'll run low when the car sits. Also said that inflating tires too high causes uneven tire wear and too low causes sidewall flex/damage. It's best to go with the recommended tire pressure for the TIRE, not the car.

Others have already said it, higher tire pressure decreases contact patch and you wont grip as hard, but will get better mpg. Lower tire pressure allows for more grip, and imo more comfy to drive on. Ask a few auto-x people they run low pressure all the time :]