Do Tires Lose Grip When The Road Surface Heats Up?

I have always thought that a tires grip increases as the tire and/or road surface heats up. I was watching MotoGP the other day and they kept talking about the tires losing grip as the surface heated up. Could someone explain this to me (including how tire pressure is part of the equation)? Thanks.

I don't know that the tire pressure part matters too much...but I do have experience with this. I was at NJMP at a track day a year or two back and the bulb temp was 105 degrees and the track temp was way higher. I was using Medium compound race tires and they were slick due running too hot! Race (and street) compounds have a temp range they 'work best in'. Too cold and they are not sticky, too hot and they get all melty which is equally bad. Typically - from track day knowledge - softer compounds for cooler days and harder compounds for hotter days keep the tire/track temp balance. Although, if the track surface temp is way hot, it is just plain slippery as I found out in NJ (and sitting in leathers in 105 degree heat is not recommended).

In general, more heat equals more grip. But, there is a temperature range where a particular tire is happy. From my autocross experience, I have seen situations, (2-drivers, hot pavement), where it was necessary to spray down the tires with water between runs to bring them back to the proper operating temperature. If not cooled down, they feel "greasy." The same tires have less grip when too cold as well.

More grip, unless the tires get too hot. :comp13:

My thought is that unless the ambient temps are really high, and the pavement is steaming you'll rarely get a tire too hot on the street. OTOH high temps can definitely make the tar snakes really slippery. :beer:

All depends on the compound. Not so much the Carcass or Tyre wall nor Pressure, Although these Latter Two play a part in the Heating up Process and Final Pressure at higher temps... basically each Model/compound of Tyre has an optimum working temperature Range. Above or Below that, watch out. Most people Experience and/or can relate to the loss or lack of grip at suboptimum temps but it Happens w overheating as well. Rubber can Melt.

I've Experienced at the Racetrack and Southern Spanish roads at 45°C Ambient temp

And I say "not so much" to do with Pressures and Tyre wall stiffness, but these do come into play... too much pressure and the contact patch is reduced... the softer Tyre walls are so the gripping contact patch is optimum when Leaned over and can depend on Tyre pressure.

There's more, much more to it but you get the idea