Depends on what your taste is. What are you looking for a low profile or a more beefy look? Go with a 17" or 18" for a lower profile. 15" or 16" for more sidewall.

Your sig doesn't say if you have RWD or 4X4. That might make a difference too.

I just noticed your truck is dropped, so I'm guessing you are looking more at a low profile set up.

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Sgtsandman's Work in Progress
2011 Ranger XLT, 4X4, 4 door Super Cab. 4.0L, 5 Speed M50D-R1HD, 3.73:1, 8.8" open differential, Jason Pace cap
2019 Ford Ranger STX FX4, Super Crew, 2.3L Ecoboost, 10 speed automatic, 3.73:1 with rear locker, Leer 100XR cap