Help! I'm rebuilding a pair of OSSA MAR wheels and dont know what measurement is required between the hub face and the rim in order for the wheels to be true and aligned when reinstalled on the bike!

knowing the type of vehicle would be nice
nuts that keep coming loose indicate the hubs are side specific with left hand and right hand threads
if you have a left hand side hub on the right hand side or vica versa , that will be the reason
next check the rim stud area
square shouldered holes in aluminium wheels require a steel washer first and rims that are tapered at the studs require tapered nuts

try putting one wheel of what you want to do on a hub to see if it fits
check for stud pattern and that the studs fit in the center of each hole
next measure the distance from the rim edge ( use a straight edge across the diameter and measure from that edge to the stud holes are ( measuring rim off set)
if both wheels measure the same then they should fit
go to a tire dealer and get the details of each rim to see if it can be done
the major items to be aware of are the stud pattern is the same pitch circle diameter ( bolts in the same circle ) and the center off set of the rim

you intend fitting ***65r -15 tyres on the car
so there will be no difference in speedo readings or mileage readings because the critical measurements as the 65 ( side wall height and the rim size 15 remains the same
the other dimension --185, 195 215 are the tread width and require a rim of suitable width to sit the sidewalls correctly so that the tyres will not roll of during cornering
What you need to know is the offset of the rims for each car
the offset is the distance from the rim edge ( measured by a flat edge across the rim) to the face of the rim where it fits against the hub
the off set is measured as positive , negative and neutral
you will have to get a bare rim of each vehicle and measure that off set
if it is not the same , the rim can hit the brake callipers, hit the internal splash guard on full turn or place excessive load on the outer bearings in the hub or foul the mudguard edge on full turns and bumps get all the information first as a mistake can make the vehicle ******* on the road , loose you your insurance and subject you to a traffic infrigement

If you're saying you want to keep your old hubs and install roadie-sized rims so you can use road-friendly and efficient tires you're looking at an expensive and wasteful project. The hubs would be the only parts that are potentially re-usable. I seriously doubt the rims you have right now are 1.95" wide. I have several mountain bikes and many wheelsets and not a single one that I can't put anything from 26x2.25 to 26x1.10" tires on. At 100-plus psi the little tires are hard as rocks and roll nice.

If you DON'T have disc the whole project is a non-starter becuase you can't arbitrarily change wheel sizes on a rim-brake-equipped bike. Disc brakes would require you to have disc-specific hubs so search the web for "700c disc wheelset" that match your disc size (if you have disc).

If you want to DIY you'll need some special tools and skills.
http://www.parktool.com/blog/repair-help/categories/wheel-and-rim-service

Then you'll have to select rims and find an online spoke length calculator so you can order the precise lengths you'll need, assuming you have data for your rims and your hubs.

Look online or eBay, too.

A Bike Shop might be willing to lace on new rims and spokes to your hubs but it will be expensive and you would be destroying presumably fucntional MTB wheels. By the time it's all ordered and installed it would probably have been cheaper and more reliable to have just purchased new wheels.

the rear spokes are the same size( yes ).

Take a tape measure and measure from the center of one hole in the rim to the one next to it. write that measurement down. Now measure from the center of one of your lug nuts on your bravada to the center of the lug nut next to it. If the measurements match exactly, the rims should fit.

While you did not mention the year, front or rear hub I have done most.
The hub bearing assembly is a sealed bearing that mounts with three bolts coming in from the axle side. An air impact gun will be required to remove the drive axle spindle nut that passes thru the center prior to disassembly. Remove the axle nut, three hub fasteners and ABS wire harness to the wheel speed sensor. Reinstall in reverse order

Is it rubbing on outside edges of drum, or in the center area? Did you double check to make sure center of drum is all the way on the hub as it should be, compared to others? I'd look real close at size of center going over hub, for no slop, and on all the way, as well as measure thickness of drum compared to others where it's rubbing. The only place you want the drum and rim touching, is at the studs and face of drum behind it. Make sure center of rim isn't bigger as well.

It sounds like you are trying to remove the hub, not disassemble bearings if you are trying to replace the rim. First off, replacing the rim requires you to rebuild the wheel, meaning re-lacing the spokes and truing the wheel. Unless you are very experinced in wheel building I sugguest you purchase a new rear wheel. Not only will it cost much less but it will save you much time and headache. Your local bike shop can help you with this. Hope this helps.

The Junior tiller does not have a neutral selection. In order to free wheel the tiller you have to remove the pins that go thru the wheel rim hubs and then it will roll without starting it. Hopefully the rims are not rusted to the wheel shaft.

Frank