One of the first questions new RZR owners ask is, “What size tires can I run?” Without a-arm modifications to your ride, the largest tires you can safely run are 26 inches – not very large for true mud riders! High Lifter Products’ Max Clearance Front Forward Arched Upper & Lower Control Arms for the Polaris RZR 900 & RZR 900 "4" gives you the clearance needed and when combined with our lift, you can run up to 31" tires! When installed without a lift, you can run up to 29.5" tires!