There's a tire that NField Gear lists for the G5 front or rear, I think it's the K81 4.10"x19". My shop was trying to fit it to a G5 front and it just barely fit in there. It was really close to rubbing the fender at the sidewall. They even bent the fender in a bit by the fork tube to make more room and it was still too close for comfort. The owner was bummed, it looked really nice on the bike but was just too close to rubbing to be safe.
Anyway, a lot of tire manufacturers have specs on their sites. You could look up and compare knowing that one is just a little too big.
Scott
Scott