My caster tires for some reason don't seem to have the spring they used to or something. The mower is riding much rougher than it used to. I did a search on the topic and all I could find was several guys foam filling these tires but I understand that will make them hard. They're already hard as a rock it seems and I was considering buying a new set but after closer examination mine seem to be in decent condition. I just don't know what to do. I have a 52" Geat Dane Surfer and since my year model they have come out with a larger caster brace ,wheel, and tires but I'm not willing to fork out nearly $400 unless I knew for sure that it would make a dramatic difference. I figure taller tire=more air =better ride. Any suggestions?