One of the best investments I made for the bike ride was when I purchased 700x27 tires instead of the standard 700x23 width found on most road bikes. I ride a aluminum frame bike with a carbon fork and seat stays, and I would usually feel every little bump I would ride over. After reading a short post by Leonard Zinn I decided I should try out fatter tires.

The $60 I spent on the fatter tires was one of the best gear choices I make. The wider tires allowed me to ride with a lower tire pressure and thus my ride was noticeably more comfortable. The new tires seemed to soak up much of the vibration that I used to feel. I was able to ride longer with less pain! Even though I'm using a lower pressure, there is minimal performace decrease. Not all road bikes will fit a 27 tire, but most all will fit a 25 which is still better than 23.

The idea tire pressure results in a 15% drop in tire height when you are one your bike. The PDF below provides a simple way to calculate what your tire drop is based on your weight. I would highly recommend figuring out your optimal tire pressure and purchasing wider tires before starting your bicycle trip. 

Download the article from Bicycle Quarterly to determine your optimal tire pressure.