Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - "Inflation pressure does not affect grip": Autospeed article.

orange4boy · 12-15-2009, 04:51 AM

All of these thing depend upon the rubber formulation, temperature, speed, application, road surface. Here I am talking about passenger tires on asphalt / concrete in normal driving conditions.

My intention is to find and present specific information regarding the relationship between traction and inflation pressure. Whenever this is discussed some people express extreme reserve at inflating to max sidewall and hysteria at inflating somewhat past max sidewall claiming all kinds of calamity and no proof of it. I think these people are misinformed. The AutoSpeed article is interesting, if incomplete, but generally sound, and gave me somewhere to start learning more. The study I posted shows a small reduction in braking distance between low and max sidewall.

My personal opinion on this, at this time, is that up to a point, and generally speaking, higher inflation pressure gives better FE (undisputed) and gives better or the same traction (unknown but suspected) up to and a bit above max sidewall to a point I don't know what that point is but I have a hunch it's somewhere around the point at which 90% of the reduction rolling resistance from slightly higher inflation has been achieved. This is not an extreme pressure. If I had tires that were sold as low RR, I might even just leave them at max sidewall but really, I would only run lower pressures if ride were my priority. Otherwise all other safety/traction,handling issues are better at max sidewall.

One of the biggest and most common dangers is actually underinflation which can lead to blowouts from temperature build up. Higher inflation pressures (not extreme pressures) reduce the possibility of blow out by reducing heat build up.

It is not my intention to give advise, just present information I have found and my opinion on it. My opinion is based on what I have read and some of it is extrapolated from that information. I am willing to change my opinion if I find credible evidence.

From what I have found so far, max sidewall reduces...
1) risk of rollover
2) failure from overheating*
3) stopping distances
4) hydroplaning
5) slipping in snow* (depending on conditions, sometimes lower is better)
6) body lean in cornering

* edited to increase clarity

The only disadvantage to max sidewall I can think of is ride quality.

12-15-2009, 04:51 AM	#30 (permalink)
orange4boy Master EcoModder Join Date: Aug 2008 Location: The Wet Coast, Kanuckistan. Posts: 1,275 The Golden Egg - '93 Toyota Previa DX 90 day: 31.91 mpg (US) Chewie - '03 Toyota Prius 90 day: 57 mpg (US) The Spaceship - '00 Honda Insight Thanks: 100 Thanked 306 Times in 178 Posts	All of these thing depend upon the rubber formulation, temperature, speed, application, road surface. Here I am talking about passenger tires on asphalt / concrete in normal driving conditions. My intention is to find and present specific information regarding the relationship between traction and inflation pressure. Whenever this is discussed some people express extreme reserve at inflating to max sidewall and hysteria at inflating somewhat past max sidewall claiming all kinds of calamity and no proof of it. I think these people are misinformed. The AutoSpeed article is interesting, if incomplete, but generally sound, and gave me somewhere to start learning more. The study I posted shows a small reduction in braking distance between low and max sidewall. My personal opinion on this, at this time, is that up to a point, and generally speaking, higher inflation pressure gives better FE (undisputed) and gives better or the same traction (unknown but suspected) up to and a bit above max sidewall to a point I don't know what that point is but I have a hunch it's somewhere around the point at which 90% of the reduction rolling resistance from slightly higher inflation has been achieved. This is not an extreme pressure. If I had tires that were sold as low RR, I might even just leave them at max sidewall but really, I would only run lower pressures if ride were my priority. Otherwise all other safety/traction,handling issues are better at max sidewall. One of the biggest and most common dangers is actually underinflation which can lead to blowouts from temperature build up. Higher inflation pressures (not extreme pressures) reduce the possibility of blow out by reducing heat build up. It is not my intention to give advise, just present information I have found and my opinion on it. My opinion is based on what I have read and some of it is extrapolated from that information. I am willing to change my opinion if I find credible evidence. From what I have found so far, max sidewall reduces... 1) risk of rollover 2) failure from overheating* 3) stopping distances 4) hydroplaning 5) slipping in snow* (depending on conditions, sometimes lower is better) 6) body lean in cornering * edited to increase clarity The only disadvantage to max sidewall I can think of is ride quality. __________________ Vortex generators are old tech. My new and improved vortex alternators are unstoppable. "It’s easy to explain how rockets work but explaining the aerodynamics of a wing takes a rocket scientist. Last edited by orange4boy; 12-15-2009 at 03:25 PM..