This is a very common problem with pneumatic rollers and there are several ways to combat it. Tire temperature, surface temperature, rubber compounds in the tire itself and or "release agents". You are correct that the problem is worse when the tires are cold. Heat is the key. Keep the tires clean. Get the tires hot and keep them hot! With that said, keeping them hot is not always possible. The size of the job can often determine whether you are able to keep the machine rolling on warm/ hot mix to maintain the temperature of the tires. Try to keep the machine moving all the times. Stopping allows the tires to cool. Some people use curtains on the tires to trap heat from the asphalt surface and keep wind from cooling the tires. New rubber compounds have been introduced to tire designs recently but these tires are often expensive and hard to come by. Now for the most common and most practical solution. Use a release agent on the tires. This is what most everyone does unless they are paving roads where the machine can stay in constant motion to keep heat in the tires. The most common release agent used is, you guessed it, diesel fuel. It is often frowned on by inspectors but it works well, it's readily available and probably the most affordable. We will typically use a pump up garden sprayer just like you use on truck beds and asphalt tools. Lightly mist the tires and coco mats if equipped. Do not saturate the rubber! Diesel fuel will break down the rubber over time and cause it to become soft and deformed. It will also cause tire valve stems to blow out. You will need to reapply anytime the tires start to "pick up". Be careful about getting on the mix when it is too hot. If it is too hot, it does not matter what you do, the tires will pick up! There are also other water soluble commercial release agents out there. Some do work but can be expensive. They can be added to the water tank of the machine and applied with the water system. That brings up another point. All pneumatic rollers have a water system but if you are rolling hot material the water will cool the tires and can cause the mix to stick. I hope this helps and I will be glad to try to offer any other information if possible.