Not sure on other years, but the XR80 and XR100 1985/86/87 used the same frame. The XR100 had the same diameter forks, but 50mm longer than the 80, and the swingarm was 50mm longer also, but the wheels were interchangable, IE: the XR80 wheels would bolt straight onto the XR100. The XR80 had 14 inch rear and 16 inch front wheels, the XR100 had 16 inch rear and 18 inch front. HTH
Yes
There is enough room on a standard 2001 Honda Civic to put wheels as big as 17 inches. The 15 inch wheels will fit perfectly.
The primary drive wheels are the front wheels - therefore, those are the wheels that should have the chains placed on them.
yes i replace my crx wheels with 17" tenzo r racing rims
yes
It is important to put correct amount of fluid in a vehicle. The Honda XR 100 has the oil capacity of almost exactly 1 quart of oil.
yes
either the wheels you put on are smaller or the calipers are bigger or even both :P
1 US liter.
yes i had 19" on my last one ,and on my one now i have 17"
you mean trucks and yes you can but the easier way is to put a bearing onto a truck then push the wheels onto the bearing
About 5 Liters according to the manual. You can never have too much oil. Nice wheels