P&G, Engine On Coasting

[spotaneagle]

I think it depends on the tires' size meaning height.. that is how well what I'm talking about works, I have 195 60 15s i'm doing this with what about you cow? vw's have short tires(60) you might be 45 height instead in that case the tire would get wider when you add more pressure, when I ad more pressure, the area on the ground gets thinner..

also truck tires require so much air that it probably weighs down the wheels more and in turn handles better

I hope I didn't shoot too many holes in your argument lol

ps riding lower to the ground in the front, could also help aerodynamics..?

[theholycow]

My VW is 3000 pounds and is equipped with 195/65-15 tires.

The same increased handling effect was quite pronounced in my 1997 Pontiac Grand Am, which was 2600 pounds on 205/55-16 tires.

I run 80psi in my truck's front tires and 70 in the rear. If I run 80 in the rear then they spin too easily on wet pavement because there's so little weight back there.

The tire does not change width with pressure. The contact patch does change shape, but the contact patch actually isn't as important for handling as you think on cars like this. The big issue is that the tire bends and deflects at its sidewall, so the tread at the inside comes off the ground and the outside sidewall starts to touch the pavement instead. That's why if you corner too fast you wear the edge of the tire. The increased pressure fights that effect.

Riding lower will help aerodynamically, but the change in height from recommended inflation to maximum inflation is minuscule, and the decrease in rolling resistance is large.

[spotaneagle]

hmm well I already have LRR tires plus my 2200 lber might not push down as hard against tires maybe heavier cars are more to that effect.. alot of cars that are small seem to have rounded tires cause they dont push down as hard maybe?

[spotaneagle]

so putting more air in a heavy cars' tires would squish the tire across the pavement as you ad it, whereas a light car adding pressure might round it off..

[Jay2TheRescue]

I don't know. My Buick has weak springs in the front, the front end rides a few inches lower than it should. It may help aerodynamics, but it doesn't handle or ride as well is it should. (although its still not bad)

[spotaneagle]

haha thats a buick not a saturn, every car is different, but regardless, My tire store told me that they wouldnt go any higher than 34 or 35 ps in a saturn, so my point is it all depends.

also a 65 height tire is a little different that a 60, The sidewall has more room to move around, especially when were comparing apples to oranges, my toyo(known for hard rubber, LRR) vs whatever cow has on, which in most cases is not of like quality to a 195/60/15 toyo tire.

;Peverything is different

[theholycow]

Except in extreme circumstances, the tire tread will remain flat against the ground; its profile does not round off unless the pressure is ridiculously high. In this post I will label that limit "ridiculous pressure".

For a given tire size, "ridiculous pressure" will be lower for a lighter car than a heavier car. Increase the tire height and/or width and you've reduced the "ridiculous pressure" level for both cars. Decrease the width and/or height and you've increased the "ridiculous pressure" level.

Decrease one and increase the other, and then some math gets involved to say how it has affected load/pressure, or just look it up on a load-inflation chart to see how it compares.

[spotaneagle]

btw stock these toyos I have are 1 inch wider than other 195/60/15 tires I've found,
except for michelin warriors, which are comparable when thinner tires get to their ends, they tend to become real dangerous, real quick

note:
Project84 is running 205's with a ton of air pressure

205 is above factory spec so adding a ton of air to that works well, not so well with 195s

[theholycow]

"Adding a ton of air" will work better for the 195s than the 205s. The 205s will reach the limit of benefits at a lower pressure than the 195s will.

[spotaneagle]

hmm not sure honestly probably still depends variably on the tire material