I got some wheel caps for my SR5 rims on my pickup, but I'm having a hell of a time trying to install them.
they are fighting me every millimeter trying to mount the, and even If I do they immediately pop off when I torque the lugnuts.

Are these the correct wheel caps for these rims or am I doing something wrong?

 

There are two types of these wheels, early and late, and the center caps do not interchange between them.
Looks like your caps are early type, perhaps your rims are not.

See this thread>>> WTB [GreatLakes]: 1986-89 4Runner stock wheels - YotaTech Forums

 

Checked out that thread, yeah look like my rims are from an early model 4Runner and the center caps are the late model ones. Wish I knew they were different before I bought em.

 

It's the other way around
Older type caps, newer type rims.

 

for the 4-spoke alloys, there were two versions during the run. the offset-15 wheels were made from '86 to '88, while the offset-8 wheels were made from '88 through '95. the early center caps will work with either wheel, but the later caps only work with the later wheels.

edit: i torque the lugs prior to installing the caps; and remove the caps before loosening the lugs.