# Why do the tyres of the vehicles burst during summer?

The explanation of most is -According to Charles' law if the temperature increases volume should also increase and hence the tires burst. But it is also that if volume increases pressure decreases (Boyle's law). So the pressure of the gases should lessen and hence tires shouldn't burst. I know there is some flaw in my logic. But I can't find it. Help!

• This tends to be due to the condition of the tires, it seems to happen more often where tires are in a "well-worn" state ie they are significantly weaker than when in "new" or "good" condition... – user207455 Jun 4 at 6:29
• I see that you live in northern India. What are summer temperatures like in your region? – PM 2Ring Jun 4 at 8:36

The volume increase of the tyre when it's hot is small, and so the pressure increase in a hot tyre is significant.

In addition, high temperatures cause rubber to weaken, which increases the chance that the tyre will pop.

By far the worst situation for a tyre is when it is not only hot, but also rolling at speed. In this condition, the flexural stresses inside the tyre are great and these stresses, plus the reduction in strength of the rubber with heat, can cause the tyre to fly to pieces.

Tyres intended for high speed use at high temperatures must be made from rubber compounds that are specifically designed to withstand heat without weakening.

• FWIW, rubber can have a negative thermal expansion coefficient at normal temperatures. See physics.stackexchange.com/q/448998/123208 I don't know how vulcanization affects that. – PM 2Ring Jun 4 at 7:28
• Wait. How the pressure can increase if volume increases ? Pressure is inversely proportional to volume. – Ali Jun 6 at 16:25
• heat is being added- that's how! – niels nielsen Jun 6 at 16:50

in summer black asphalt in mid-day gets very hot, tires flexing as they roll generate more heat, the rubber compounds soften. the air pressure increases as the air heats and expands. All these conditions adversely affect aged tires. Also tires aired up to 32 psi in the coldest of winter can easily go up to 38 psi or more just sitting in your driveway on a hot summer day. Tire pressure should be checked several times a year.