# Best Tire Air Pressure

**URL:** <https://community.cartalk.com/t/best-tire-air-pressure/166679>\
**Category:** Maintenance/Repairs\
**Tags:** 330, bmw\
**Created:** [July 1, 2020, 7:30pm UTC](https://community.cartalk.com/t/best-tire-air-pressure/166679 "2020-07-01T19:30:16Z")\
**Posts on this page:** 4\
**Page:** 2

<div class="post-metadata">

**Author:** ![tom418](https://avatars.discourse-cdn.com/v4/letter/t/da6949/32.png) [@tom418](https://community.cartalk.com/u/tom418)\
**Post date:** [July 4, 2020, 12:54am UTC](https://community.cartalk.com/t/best-tire-air-pressure/166679/21 "2020-07-04T00:54:55Z")

</div>

Being trained in the aviation industry, I always use the maximum specified pressure for the car, as placarded on doorjamb, glove box, etc.  
We were taught that hydroplaning speed (in knots) is nine times the square root of the tire pressure. (MPH would be knots times 1.15)

More pressure in tires would be safer- to a point. Too much, and you lessen contact area and wear out middle of tread faster.

---

<div class="post-metadata">

**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\
**Post date:** [July 4, 2020, 12:59am UTC](https://community.cartalk.com/t/best-tire-air-pressure/166679/22 "2020-07-04T00:59:28Z")

</div>

> [@JoeMario](#):
>
> This is supposed to be from an early 60s Chevy, though I don’t recall such a wide front-to-rear difference.

I bet it’s from a Corvair, the difference was needed to control the handling.

---

<div class="post-metadata">

**Author:** ![jtsanders](https://avatars.discourse-cdn.com/v4/letter/j/c2a13f/32.png) [@jtsanders](https://community.cartalk.com/u/jtsanders)\
**Post date:** [July 4, 2020, 2:01pm UTC](https://community.cartalk.com/t/best-tire-air-pressure/166679/23 "2020-07-04T14:01:18Z")

</div>

> [@tom418](#):
>
> We were taught that hydroplaning speed (in knots) is nine times the square root of the tire pressure. (MPH would be knots times 1.15)

Or you could just use 10 times the square root of MPH. It’s good to see the derivation, though.

---

<div class="post-metadata">

**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\
**Post date:** [July 4, 2020, 2:26pm UTC](https://community.cartalk.com/t/best-tire-air-pressure/166679/24 "2020-07-04T14:26:02Z")

</div>

So I should beware going over 59-63 mph in the rain with my tires at 35-40 (cold vs hot) psi.

[![](https://global.discourse-cdn.com/cartalk/original/3X/9/8/9824443f6256e5c0c044bb73a67d72a1124e7f91.jpeg "Car crash: too fast for conditions") ](https://www.youtube.com/watch?v=Wd9-JbuRz-w)

[Previous page](https://community.cartalk.com/t/best-tire-air-pressure/166679.md?page=1)