Could the tires be developing flat spots from sitting? If so, they should round into shape with some high speed cruising to get them good and warmed up. Surface rust on the brake rotors is another possibility. Again, use is the cure.

 

 

How long at a time does the car sit?

 

It is the tires. Assuming the car only sits for a week or two, it should be reversible after you drive the car for a while. However, much depends on the manufacturer and type of tire. When it comes time for you to replace the tires, find one that has a hard compound. The easiest way to tell is to look for a tire that is rated for the longest mileage. Any ultra high performance tire will be softer and have a shorter life and be more susceptible to flat spotting.

One method to help reduce flat spotting is to inflate the tires to close to their maximum psi while the car is stored. Of course then you have to reduce the pressure before you drive it and then re-inflate when it goes back into storage.

 

You could always buy a set of these ramps to park the car on.

 

 

Some tires are more prone to flat spotting than others. 2010 model here, 43k miles, so it sits. It sits sometimes a couple to 3 weeks at a time. The Pirellis so far I haven't noticed flat spotting.