detecting tire pressure

**st_claire** · 10-04-2007, 04:22 PM

Hi,

I rented a car last weekend, and it's onboard computer knew the pressure of each tire. I want to put that into my car. Has anyone done this? I figure all you would need is a pressure sensor for each tire, but not sure how you would go about connecting it, i.e. wireless or wired, and power becomes an issue if wireless. Anyway, if anyone has done this, I would love to hear about how you went about it.

Thanks!

**BarryWoods** · 10-05-2007, 12:07 AM

A buddy of mine put tire pressure sensors in his Saab. They make kits for it. Pretty slick looking too.

**2k1Toaster** · 10-05-2007, 01:10 AM

The easiest way to do it is the first way it was done by Porsche. Monitoring individual tire speeds as they rotate.

An underinflated tire will have a smaller diameter. Smaller diameter covering the same distance, means it rotates faster. Now "faster" is compared to the other tires. You can have up to 3 rotating faster because if all 4 were faster, then they would be the same if that makes sense. So by monitoring each wheel's independant speed, you can detect up to 3 simultaneous low pressure. And since all ABS enabled cars have individual speed sensors already all you have to do tap into all 4 and monitor them.

**st_claire** · 10-05-2007, 10:04 AM

Do you have a link to the kit your friend used?

The speed monitoring idea is good, but I would like to be able to tell the exact pressure of each tire, not just if they differ from one another.