Hi, I'm trying to find out the maximum tire size i can use. I have Alex PRD-15 rims and can't find specs on them. they came with 700cx25 tires. Looking on Sheldon Brown's page, it seems that most rims that will take a 25 can take a 28 as well, which is the size I want. can anyone confirm / deny? Also, what is the most accurate way to measure clearances? The bike is a Fuji Newest 3.0 54cm, if that helps any. Thanks.