Yeah I don't think you'll gain 2" on the axle. But it could depend on the tire too. The rear Razr 2's on mine are supposed to be 20" tall, and I just went out and measured them, and there a little over 19" go figure...
I'm curious to hear your results... be sure to post them!

 

Yup. Ill be sure to measure the OEM 20 inch tires and axle clearance on concrete in order to make a comparison to the after market 22 inch tire measurments. The way I see it unless the tire size is bogus or a lie, like shoe size it has to be taller, just like tall car and truck tire sizes, I raised the ground clearance on my little Nissan 4x2 by placing the tallest tire size they make and made a big difference in ground clearance although Im now geared taller. Anyway its pretty non-intrusive for a mod so the worst that can happen is I will have to live with them until they wear out LOL.

 

remember if you go taller tires you will have to regear for them because you will loose some bottom end but you will gain top end speed. I know I tried it once

 

Yup. I already installed a 13 tooth countershaft sprocket (down from 14 OEM) and ordered a 44 tooth rear sprocket (down from 40 OEM). The 13 tooth front made a nice difference eliminating the need for a larger flywheel in the tight slow stuff eliminating all stalling when crawling up steep rocky hills. If the new rear tires turn out to give me 2 inches and gear me taller, I will just slap on that 44 rear which in conjunction with the 13 front should take care of any tall gearing concerns LOL.

 

Update on LTZ400 axle clearance. Using the LTZ400 Calculator to determine how 22 inch rear tires will affect my gearing it looks like 13/43 sprockets will not compensate enough for the tire size increase in gearing. So I ordered a 12 tooth DRZ400 sprocket since they don't make one for the LTZ400 and drill pressed the two holes in the sprocket for the securing bolts on the LTZ. Looks like it will work and bring me back into lower then stock gearing I am used to but now with 2 more inches more tire axle clearance. This in conjunction with the 23 inch fronts will not only give me more clearance but a smoother ride as larger tires roll easier.

 

I have a 12 tooth front sprocket and a 44 rear on both my wifes and my Z400's and like this ratio. I ordered the 121 tooth from Sidewinder (note adds in atv magazines) and 44 from Suz dealer.