Looking to order aftermarket wheels they are 18x9 with -12 backspacing, tires are toyo open country m/t which are 12.50 will this combo work without rubbing ?

 

Yes.

 

RIght. And -12mm is the offset, not the backspacing. Just two different ways of measuring the same thing.

 

How do you work out what your backspacing/offset should be, so I know for future reference

 

Keep the chart that Tripletsi posted, that's good info!

 

It may as well be in Dutch. If I get 35x12.5r17 wheels what backspacing does it need to be will a backspacing of 4.75" work?

 

Lol, Dutch is confusing. Look here, this will help you figure out what you need: https://www.jk-forum.com/forums/modi...relate-136663/

 

Forums like this are your best source of info because it varies from vehicle to vehicle. In your case, for a JK Jeep, a 9 inch wide wheel with 4.5 inches of backspacing is the most common. 4.75 inches of BS will also work fine. To give you an idea how much it can vary, my wife's Expedition is running a 9.5 inch wide wheel with 6.7 inches of backspacing. Every vehicle is gonna be a little different.