Why does the owners manual say to increase tire psi to 38 when driving over 100mph?

[white lightning]

Won't doing so decrease traction?

[Eugenio_SS]

to decrease resistance, so one can get better fuel efficiency, by sacrificing grip, though.
I wouldn't do it.

[Corvettekid82]

I'd think it would compensate for the expansion of the sidewalls from spinning so fast. You know how the sidewalls flex like mad on Drag radials when they burn out.. wouldnt street tires expand a bit as well at high speeds?

[predator]

my guess would be that low tire pressure will increase heat production do to more deformation of the sidewalls. at 100 mph your getting twice the deformation per second as you would be at 50 mph means around twice the heat... heat and tires arent good... seperation and blow outs could occur.

only my$.02

and grip is caused by friction... and your thinking if you inflate your tires youll loose size on your foot print... and friction actually has nothing to do with contact area, only force applied (weight) and friction coefficeint.

[Eugenio_SS]

I'd think it would compensate for the expansion of the sidewalls from spinning so fast. You know how the sidewalls flex like mad on Drag radials when they burn out.. wouldnt street tires expand a bit as well at high speeds?
no... since they are constructed of steel layers as well as nylon layers.

[Eugenio_SS]

also, another thing to remember is that @ higher speeds, you increase the tire temp, which increases the pressure already... no need to increase it even more and change the contact patch shape.

[bbfirebird]

also, another thing to remember is that @ higher speeds, you increase the tire temp, which increases the pressure already... no need to increase it even more and change the contact patch shape.

i second this.

[Corvettekid82]

things that make you go 'hmmm'