18 laced or 19 laced ?

For my tracker build i have a radian swing arm and gsxr forks. I plan to use a cognito moto fork conversion and front wheel hub with the gsxr donor.
Both my rims are apart and with the new hub on the front I have the choice of getting another rim then lace them both at 18 inch or both 19 inch. I understand trackers usually are 19 inch but i want road orientated tyres so could go either way.
Please advise pros and cons.
Thanks in advance. Mitch

It may be difficult to find rear tires in 19", other than that it is only an inch difference so lookswise it would be about the same.

Couple shots of resto with WM5-18 front and rear rims shod with Michelin 110/70/18 front tires I had to change the rear to a 140/70/18 Shinko podium rear
(excessive wear). even 18" tires aren't easy to find.
You can see where I lowered the fender to better fit the tire.

If it helps, this thread has a pic of my bike. 19" front, 18" rear, 340mm shocks, Bridgestone BT45 tyres: http://www.xs650.com/threads/question-for-those-with-powdercoated-hubs.51837/