Keeping your pressure under control
So why care about your tire pressure? There are a few reason: Punctures can be dangerous and affect riding performance, riding off-road is usually better with lower pressure and the basic fun science thing of what is going on while riding and how can it be measured. I also noted that good riders (Simon!) usually care quite a bit about their pressure while riding with them.
These days there are monitors that keep track of the pressure in a wireless way. While looking for one I did a bit of Googling and found the SYKIK Rider SRTP300 to be a popular choice. So I ordered one and it showed up a couple of weeks later.
Fixing the problem
Testing it out
We have four observations to test this out on:
Front wheel 1.9 bar @ 32 C and 2.0 bar @ 33 C
Rear wheel 2.0 bar @ 33 C 2.2 bar @ 40 C
The law says P / T = k which means (1.9 + 1) / (273.15 + 32) = 0.0095 for the front tire at start.
0.0095 x (273.15 + 33) - 1 = 1.91 so not quite 2.0 so possibly we could just jumped from 1.94 to 1.96
Lets try the rear wheel
(2.0 + 1) / (273.15 + 33) = 0.0098 which will give our prediction
0.0098 x (273.15 + 40) - 1 = 2.07 so not quite the 0.2 jump as expected but roughly in the right range