Higher tire pressures

<div class='quotetop'>QUOTE(ibcs @ Aug 21 2006, 09:01 AM) [snapback]306752[/snapback]</div>

I have been using 44 lbs in all four tires for over 20K miles and there are no problems. This car is going to try to understeer (push) if you drive it to hard into a corner anyway (VSC may prevent this to some degree). The 2 pound front/rear difference simply doesn't make any difference. Conversely the 2 pound difference doesn't hurt anything either.

 

Hey Everyone,

I just ordered the Continental ContiProContact tires from Discount Tire. They are rated at 10 more estimated mileage than the EOM integritys, and have a lower rolling resistance factor of .00825. In addition, I found some reference to 50 plus PSi capability. I already run my OEM's at 45/43, so I can imaging that 52/50 will yield even better mileage. though my ever widening butt may notice the difference.

 

One thing to consider with tire pressures--the change in the pressure with temperature. Assuming the volume of the tire (or the density of the air within) doesn't change, then the pressure of the tire will be directly proportional to the temperature in Kelvin. So...let's say it's 45 deg F (which is 7 deg C or 280 deg K) and you fill up your tires to...say...42 psi. Then...if it warms up to 70 deg F (which is 21 deg C or 294 deg K), you'll be at a temperature that's 5% higher in Kelvin...and thus your tire pressure will also go up 5% from 42 to around 44, the maximum recommended pressure, at least with the standard tires that you get with a new Prius. Thus...any higher temperatures, and you'll be above the recommended pressure (which I'm sure allows for some leeway--though I don't know how much).

Of course, add to that any increase in temperatures in your tires due to friction while driving--though I always fill my tires when they're warm (kind of have to, since I'm not exactly keen on filling up my tires at home with my bicycle air pump!!!).

Thus...one should use their normal temperature ranges to guide how much air they put in their tires (also a good idea to help improve gas mileage in winter, since your tires will have lower pressures during cold weather--of course, remember to reduce the pressure a bit once spring comes).

 

<div class='quotetop'>QUOTE(westcornersville @ Feb 12 2007, 07:43 PM) [snapback]389305[/snapback]</div>

That is only true of gases whose behavior follow the ideal gas law. Based on the statements made by many people in this forum, my conclusion is that many of them are filling their tires with gases which apparently do not obey the ideal gas law.

Example: "By filling your tires with nitrogen, they become less sensitive to pressure variation with temperature."

:lol: :lol: :lol:

 

B) I consider tire pressures [within reasonable limits] to be a matter of preference regarding ride and handling. On my 2004 Prius, I ran 42 front/40 rear for over two years with the Goodyear Integreties. When I traded for my 2007 Touring Edition [glad to get the 16" wheels and Bridgestone Turanza tires], I tried the 42/40 psi and was not happy with the ride and handling so I reduced to 37/35 psi. I'm confident I will take a little hit on the MPG. It's difficult to judge MPG right now since I have less then 2,000 miles on the odometer.

I will trade off a few MPG for better ride and handling.

 

The tires on the Touring have a lower aspect ratio which means that the sidewall is shorter.

The shorter sidewall makes a "stiffer" ride and better cornering power.

 

<div class='quotetop'>QUOTE(priusenvy @ Feb 13 2007, 12:07 AM) [snapback]389405[/snapback]</div>

Pretty funny! Of course, they should be reminded that deviations from the ideal gas law are pretty small at the sorts of pressure all of us fill our tires with (except for those who are really grossly overinflating their tires--beyond what any service station air pump will allow!!!).