I gotcha, so would the best way be to use a buddy's 4th gen and mount them to see if they will clear?
Do you have a 4th gen 4R? If so -- why use your buddy's?
The only thing to be concerned about is brake clearance; if your 4R came with 16" wheels, then a set of 16" wheels from a 3rd gen will fit.
If your 4R came with 17" wheels and is a Sport or Limited version, then you may have the larger brakes, and 16" wheels won't fit.
Just the presence of 17" wheels on the 4R from the factory doesn't mean you have larger brakes though -- my 4th gen SR5 came with 17" wheels and the standard (smaller) brakes. I use 16" wheels from a 3rd gen (actually, IIRC, from a Tacoma) for my snow tires.
Do you have a 4th gen 4R? If so -- why use your buddy's?
The only thing to be concerned about is brake clearance; if your 4R came with 16" wheels, then a set of 16" wheels from a 3rd gen will fit.
If your 4R came with 17" wheels and is a Sport or Limited version, then you may have the larger brakes, and 16" wheels won't fit.
Just the presence of 17" wheels on the 4R from the factory doesn't mean you have larger brakes though -- my 4th gen SR5 came with 17" wheels and the standard (smaller) brakes. I use 16" wheels from a 3rd gen (actually, IIRC, from a Tacoma) for my snow tires.