Before you buy a set of mud tires, make sure to check the manufacturer's Suggested Retail Price (SRP). This is the price range your item should fall within. If the item you want costs too much, though, buying online could potentially save you a good value. Amazon is a good place to start; many sellers offer 18-inch mud tires at up to 20% less than the suggested retail price.
Driving conditions can play a large role in determining your final price. Off-road models need to have more suspension and higher ground clearance to handle the rigors of rocky roads. For general driving on smooth roads, a stock tire with sufficient tread depth and width will do. For mud and rock crawling, though, special tires are necessary to maximize traction and prevent the vehicle from slipping out of the hole. Look for reviews of 18-inch mud tires online and compare prices and features between different manufacturers.
If you can't find the right size tire, you'll need to know what you're looking for. There are two main types of tires used for off-road driving: stock (or original) and high performance. The difference lies not in size but in tread depth and width: the former has thicker and broader tread, while the latter has narrower shoulder and tread.
Stock tires have small tread grooves made of rubber that are spaced apart to maximize friction and reduce noise. These tires must have deep grooves that cover at least two percent of the tire's width to perform well on rough or rocky roads. High-performance tires have deeper grooves that cover at least three to four percent of the tire's width. This helps produce improved traction and control. When shopping for new tires, take note of both the deep and wide grooves to ensure the right fit.
Different manufacturers use different types of technology to improve traction. Some use solid grooved rubber on their high void tread design; others use deep grooves. Manufacturers with deeply grooved soles use the same technology as stock treads. A manufacturer using solid rubber has the advantage of improved traction, longer life, and less maintenance.
A manufacturer's decision to use either bead-styled or wedge-styled soles can alter the way your tires perform. Determining whether to use flat or convex wedges affects both your maneuverability in the mud and your ride quality.
The final major difference between stock and 18-inch mud-terrain tires is the type of tread block used. Stock tires use steel strips or solid wheel construction. Mud-terrain tires are usually equipped with a sipe design that provides improved traction in mud. Both types of tread blocks have advantages and disadvantages. Although it may not appear as much, the addition of a sipe to your tire can make a tremendous difference when driving in mud. Choosing the right tread block can be a complex decision that you should only make after speaking with a tire dealer and receiving a recommendation based on your own personal situation.