View Single Post
Old 02-05-2008, 12:50 AM   #28 (permalink)
cfg83
Pokémoderator
 
cfg83's Avatar
 
Join Date: Dec 2007
Location: Southern California
Posts: 5,864

1999 Saturn SW2 - '99 Saturn SW2 Wagon
Team Saturn
90 day: 40.49 mpg (US)
Thanks: 439
Thanked 532 Times in 358 Posts
Blackbird -

Quote:
...
I do however feel that the car's tires, being your only connection with the ground, should not be the right place to reduce the car's fiction from the reasons I listed earlier.

We may agree to disagree on it.

...
I understand your concern and I agree with being "cautious first". I am not going to talk about the contact patch issue for the moment because I think I would need to do more research on that.

Instead, I am going to talk about the load specifications of the tire. Here is my tire :

Continental ContiProContact
http://www.tirerack.com/tires/Spec.j...rtnum=965HR5CP

The load index is 91, which means each tire can support up to 1356 lbs. The speed rating is "H", which means the tires are good up to 130 MPH. I got these tires because they have the highest max PSI rating (51) available for my car and have an "LRR Pedigree" in independent tire testing.

What does this mean from my POV? This means that the tires are rated for the following maximum loads :

51 PSI @ 130 MPH @ 5424 lbs

The 5424 lbs is because each of the four tires are rated at 1356 lbs, so 4*1356 = 5424 lbs. Now, my car is placing the following loads on my tires :

2806 lbs / 5424 lbs = 0.5175 => 52% of maximum weight load.
I added about 350 lbs to include myself, one passenger, and crap.

80 MPH / 130 MPH = 0.6154 => 0.62% of maximum load.
Now, I never hit anywhere near 80 MPH, but I want to show the upper limit of how fast I would be willing to push the car if I was forced to.

From the above, it is my opinion that I am operating well within the "maximum load" of the tire. I am conservative in the sense that I am running at 51 PSI, the maximum rating for the tire. However, because I know that my other loads on the tire are at or below 60%, I don't think I would have a problem upping the pressure to 60 PSI.

CarloSW2
__________________

What's your EPA MPG? Go Here and find out!
American Solar Energy Society
  Reply With Quote