Tire pressure?

[1stToyota]

If over-inflation wasn't ONLY about increased fuel economy, we'd be seeing actual real world test results with handling, braking, etc..., comparing the results of tires that have normal pressure with those with double pressure, not just fuel economy increases, or do the 60p.s.i.ers and the websites they go to consider *safe* being a tire that didn't blow out? I'd like to see some real test results of two cars being track test against each other. I'm betting the car with over-inflated will come in 2nd in every catagory except fuel economy.

[YarisSedan]

Originally Posted by 1stToyota

If over-inflation wasn't ONLY about increased fuel economy, we'd be seeing actual real world test results with handling, braking, etc..., comparing the results of tires that have normal pressure with those with double pressure, not just fuel economy increases, or do the 60p.s.i.ers and the websites they go to consider *safe* being a tire that didn't blow out? I'd like to see some real test results of two cars being track test against each other. I'm betting the car with over-inflated will come in 2nd in every catagory except fuel economy.

http://www.popularmechanics.com/blog...s/4199963.html

[SeaYa]

Originally Posted by 1stToyota

If over-inflation wasn't ONLY about increased fuel economy, we'd be seeing actual real world test results with handling, braking, etc..., comparing the results of tires that have normal pressure with those with double pressure, not just fuel economy increases, or do the 60p.s.i.ers and the websites they go to consider *safe* being a tire that didn't blow out? I'd like to see some real test results of two cars being track test against each other. I'm betting the car with over-inflated will come in 2nd in every catagory except fuel economy.

Thank you! I tried something like this! Snowy parking lot (1-2 inches) and brought my pump. Did 30 psi and 45 psi two times each on a 20 mph turn in the middle of the lot. Here's what happened: 30psi, better traction, worse handling. I slid about 7 feet from my intended line of travel with the car pointed to the outside of the turn. At 45 psi, I had worse traction, but better handling. I slid nearly 12 feet from the intended line of travel, but the car was pointing nearly straight on the way I wanted to go. Did some reading and thinking and maybe this is why: The Yaris is a very light FF, and with an empty trunk, any increases in tire pressure will have a more dramatic effect on the rear tires, eg, smaller contact patch. Since there is already so little weight back there, the rear tires slip to an even greater degree than the front when at 45 psi, hence, the back sliding around more cuts down on the under steer, and you get the feel of better handling. Traction though, another story, I slid 5 extra feet off the 'road', which in straight line braking, could mean running into the hazard you were "looking ahead for and planning for, but still hit because I sacrificed my vehicles engineered performance for an extra 2 MPG"..and by the way, to all the 60psi people...I can't find your actual MPG savings on this post.

To the OP: I've done 35psi (42/44mpg) and 40psi (42/ 47mpg).

Seems to me like the hypermilers are trying to beat the EPA rating by as much as possible for bragging rights. Otherwise, why stop at 60? Why not do 100psi? If your answer is because the tire will burst, then you admit to already pushing the engineered limits of your tire. Otherwise, if traction isn't important to you, why not buy 3 extra spares and run them at 80psi? They're only rated for 60psi, but you don't seem to have a problem with doubling manufacturer recomendations. Let me know how that works out for you.

[1stToyota]

Originally Posted by SeaYa

Thank you! I tried something like this! Snowy parking lot (1-2 inches) and brought my pump. Did 30 psi and 45 psi two times each on a 20 mph turn in the middle of the lot. Here's what happened: 30psi, better traction, worse handling. I slid about 7 feet from my intended line of travel with the car pointed to the outside of the turn. At 45 psi, I had worse traction, but better handling. I slid nearly 12 feet from the intended line of travel, but the car was pointing nearly straight on the way I wanted to go. Did some reading and thinking and maybe this is why: The Yaris is a very light FR, and with an empty trunk, any increases in tire pressure will have a more dramatic effect on the rear tires, eg, smaller contact patch. Since there is already so little weight back there, the rear tires slip to an even greater degree than the front when at 45 psi, hence, the back sliding around more cuts down on the under steer, and you get the feel of better handling. Traction though, another story, I slid 5 extra feet off the 'road', which in straight line braking, could mean running into the hazard you were "looking ahead for and planning for, but still hit because I sacrificed my vehicles engineered performance for an extra 2 MPG"..and by the way, to all the 60psi people...I can't find your actual MPG savings on this post.

To the OP: I've done 35psi (42/44mpg) and 40psi (42/ 47mpg).

Seems to me like the hypermilers are trying to beat the EPA rating by as much as possible for bragging rights. Otherwise, why stop at 60? Why not do 100psi? If your answer is because the tire will burst, then you admit to already pushing the engineered limits of your tire. Otherwise, if traction isn't important to you, why not buy 3 extra spares and run them at 80psi? They're only rated for 60psi, but you don't seem to have a problem with doubling manufacturer recomendations. Let me know how that works out for you.

Good rule of thumb for them is to just throw their gauges away and air the tires up until they resemble motorcycle tires...bet their cars will corner better with a little bit of body-english.