Mostly cloudy this morning, then becoming partly sunny. A chance of showers. A chance of thunderstorms this afternoon. Much warmer with highs in the mid 70s. Southwest winds around 5 mph. Chance of rain 50 percent.
XL means Extra Load range which indicates the tire has a higher Load Index and Maximum Inflation Pressure (usually 51 psi instead of 44 psi) than a Standard Load range tire of the same size.
RE: XL rating for car tires. There is an engineering answer to your question - and then there is the every day good advice type of answer. I'm going to give you the latter, but if you want to talk in depth about the relationship between speed ratings and load ratings, just ask.