This might have been discussed already, and if it has, I apologize. But has anyone heard of the "max pressure - 10%" rule of thumb? I ran across it yesterday reading the tire bible (http://www.carbibles.com/tyre_bible.html) and the author actually owns a Honda Element.

I've got Toyo Open Country H/T's and the max pressure (in really small print, NOT the max pressure under load) is 40psi. Using the formula: 40-(10% of 40 = 4) = 36psi. I set all my tires to that pressure yesterday and noticed the steering felt lighter and crisper with no discernable increase in ride roughness. The author of the tire bible actually sets his tires to 37psi. So it seems this rule of thumb is a better place to start compared to Honda's recommendations . . . at least, if you want more of a sporty feel.

I fill my tires to a few lbs less than max cuz I question the accuracy of gauges.

I assume hi pressure makes tires more puncture resistant and gives better mileage, but maybe makes em more blow-out prone if hitting a sharp edge on a pothole, etc.

I fill my tires to a few lbs less than max cuz I question the accuracy of gauges.

I assume hi pressure makes tires more puncture resistant and gives better mileage, but maybe makes em more blow-out prone if hitting a sharp edge on a pothole, etc.


Gauges - I buy good gauges and have a master calibrated gauge at home. I have been burnt by gauges that have been off over 10psi. I always recomend getting a good gauge. (That does not mean exspensive) :cool:

At the volume of air typically in the standard tire used on an Element or motor vehicle, several psi either way from recomended psi will not really make much difference towards a blow out. (Wear and performace, Yes) Its been my experience that more air is better typically for potholes, because at lower pressures your tire wall will be ore likely to flair out and deform more placing the slim tire side wall closer to the sharp edges.(Clinch Flats - Off road vehicles & mountain bike guys know about these all too well) On the other hand more air pressure in the tire will translate more force of the impact into your suspension system!

At the end its your preference! :D I personally run higher pressures, but each to their own! :D

This might have been discussed already, and if it has, I apologize. But has anyone heard of the "max pressure - 10%" rule of thumb? I ran across it yesterday reading the tire bible (http://www.carbibles.com/tyre_bible.html) and the author actually owns a Honda Element.

I've got Toyo Open Country H/T's and the max pressure (in really small print, NOT the max pressure under load) is 40psi. Using the formula: 40-(10% of 40 = 4) = 36psi. I set all my tires to that pressure yesterday and noticed the steering felt lighter and crisper with no discernable increase in ride roughness. The author of the tire bible actually sets his tires to 37psi. So it seems this rule of thumb is a better place to start compared to Honda's recommendations . . . at least, if you want more of a sporty feel.


The 10% rule is not a bad rule of thumb. I personally like mine a smidge higher on my current tires! Nice Thread!:D

This might have been discussed already, and if it has, I apologize. But has anyone heard of the "max pressure - 10%" rule of thumb? I ran across it yesterday reading the tire bible (http://www.carbibles.com/tyre_bible.html) and the author actually owns a Honda Element.

Nice find - that's my site. :-D
I keep wondering whether to link it in my signature or not.

Most tires have a 'max load at max pressure', not an absolute max pressure.

The weight of a loaded Element is around 65% of the cummulative max load rating of stock tires. Your 10% rule ignores the weight of the vehicle. For the same size tire, Toyota recommends tire pressures 4 psi lower on the RAV4 (1997) and for the Element - which makes sense considering how much lighter the RAV4 is.

For the truck tires, there are published tables of pressure v load for various sizes. It is not easy to find that kind of data for cars, and probably it isn't all that necessary. For most purposes, the pressures recommended on the door sticker are a good starting point.

paulj

For most purposes, the pressures recommended on the door sticker are a good starting point.
That's too easy. :-|

Actually, this is a fascinating thread. Keep it up. I bookmarked your site, chrisell. Yes, add it to your sig. So where do your originate, where tyre is spelled like a Biblical town? We don't have to watch out for you, driving on the wrong side of the road, do we?

I looked at the Car Bible article a bit more. Note that the author's tires (for his Element) have a 40psi max, but the HPs (according to GY spec tables) have a 44 psi max. Same goes for my Coopers. BFG TA KOs in stock size have 50psi max. - by the 10% rule some of use would run 36 psi, others 39, and yet others 45 - all for basically the same size tire!

I think it is reasonable, though, to start with the door sticker pressure, and play with it to find a ride and handling mix that you like. Also check the wear pattern - though may have to wait 5k for a significant wear distinction to appear. Running somewhat harder than the sticker probably is a good idea with the Element, especially with the stock tires which seem prone to outside tread wear (due to a narrow, rounded shoulder tread?)

The Car Bible has some good notes on contact patch, such as the change in shape with change in tire size. However his discussion about Fdef and Cdef needs some editing.

paulj

The Car Bible has some good notes on contact patch, such as the change in shape with change in tire size. However his discussion about Fdef and Cdef needs some editing.

paulj

Works for me - the more input I can get, the better and more informative the pages become. As for the 'tyre' part of it, yes I'm from England but I've been going native for over 5 years now. Plus I grew up in Holland so as far as I'm concerned, it's the English that drive on the wrong side :-)
Oh, and consider my signature changed :-)