All good things must come to an end, including the tires on your riding lawnmower. Even if wear on the tires themselves isn't apparent by sight, if it's clear that the mower doesn't have the traction it used to, it may be time to consider replacements. Except in the rare instance of puncture, it's generally a good idea to replace at least the two front or two rear tires at once, so that balance isn't affected and the tires wear evenly.
Before removing the old tires, take a moment to learn something about the functioning of your mower from the tires' wear patterns. If the front tires are wearing out much faster than the rear, there is a load imbalance that needs to be corrected. Generally, 60 percent of the load should be toward the rear.
Distinctive grooves worn into the tires may point to other balance issues, or a need to rotate more often. Make repairs or adjustments as necessary to avoid having to replace the next set of tires so quickly, or even to prevent another part from failing.
Look for ties with a high "rubber to void" ratio. This means that there is a lot of tire material and little air. Such a configuration ensures good traction even as it is easier on the grass.
Take a moment to consider the terrain the mower rides on. If it is mostly flat and level, you'll want wide, smooth tires that damage the turf as little as possible. If berms, inclines and uneven ground are involved, your tires will need to offer superior traction capabilities. Unfortunately, these will make deeper impressions in the lawn.
Determine the size of the tires to be replaced. Measure the diameter of the rim, not the tire. Alternatively, look for the size listed on the old tire, or consult your repair manual.
With your terrain needs in mind, choose one of the basic models of lawn tractor tires.
Smooth: The lack of tread is very easy on foliage but provides little traction.
Rib: Parallel lines along the length of the rolling direction of the tire are a step up in traction.
Sawtooth: The lines are zig-zagged. This is another step up for tire holding power, but a step down for turf damage.
Multi Trac, Grasshopper or Mowku: Yet more traction.
Studded: If you can't get over those steep inclines any other way, use these, but your lawn will need a day or two to recover.