I knew from the start I was keeping my 16 in the rear. Looks like the 18 raises the rear too much for the look I was going for. Just need to lower the front and air ride the back and I'll be all done Just my 2 cents...

 

with the 21" tiy will have to drill the rear mounting bolt holes on the front fender 1/8" bigger and tip the fender foreward. Tape a nut to the tire and test rotate. With a metz tire I fet 3/8" clearance between fender and rubber.

I went with the 17" rear so I could get a 200mm rear tire. all I could have gotten with the 18" was a 180mm. Hind sight...I would have gone with the 18. It just has a higher coolness factor than the coolness of a fat tire.

I did not want to drop the extra cash for the rear wheel as well but YES, it can be seen and people will Always remind you of that. You will always know it too.
I lookat it as banging your own sister. sure it's a piece of a$$ but "hey man, thats your sister. it aint right".

 

Again,
The ride height for the 16 and the 18 are the same.

 

no they are not. the 150/70/18 is taller than the 150/80/16. its not a bunch, but it is taller. heres the specs from metzler


150/80B16 TL 71H R 3.00 3.00-4.00 6.02 25.43 761 40/42
150/70B18 TL (70V) R 4.00 3.00-4.50 5.87 26.26 739 40/42


over 3/4" diameter, which will net 3/8-1/2" in ride height difference


heres the same data from avon:
150/80B16 77H MT3.50 3.00 - 4.00 150 5.90 641 25.20
150/70B18 70V MT4.25 3.00 - 4.50 148 5.80 665 26.20

 

of course there is the 23" up front now-ride safe

 

where are the pics????

 

 

I would say most people go 21/18 for looks alone. Like mentioned the 18 is slightly more visible. I am also very pleased with the ride and handling as well. I use progressive springs, race tech gold valve emulator, 15 W fork oil up front. I also got a set of 440's on ebay for cheap and use them on the rear.