What are you going to spin your motor to. At 6500 rpms, with a 4:10 gear a 26" tall tire will get you to about 120. Unless you think you will trap higher than that I would say 28's would hurt you, but if your only spinning the motor to 5500 the 28's may be the better choice. As for the looks, I think a 28' tall DR looks better stuffed into the wheel well.