His current bike is a 40 pound slug. I've used Kenda Kwests. They are a decent general purpose tire but no tire is going to turn the Farm and Fleet BSO into a good quality bike that is fun to ride. That's why I suggested not attempting any upgrades on it. Save the money for a better bike. Once you have ridden a really fine road bike (a mid70s vintage Motobecane Le Champion in my case) no entry level bike will ever satisfy you.