SCORE Journal


SCORE Journal - The Official Publication of SCORE Off-Road Racing

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TOUGH TREADS Tire Manufacturers Explain Why Off-Road Tire Trends Are Changing By Dan Sanchez When Baja racing started more than five decades ago, the tires used were nothing more than street tires with modified tread patterns. Blow-outs were common from rocks on the course and racers often had to carry at least two sets of replacements with more spares at pre-determined pit stops along the course. By today’s standards, flat tires still occur but are fewer than ever before. Tire technology has taken the off-road race tire to higher levels of performance, endurance, and sizes that improve traction as well as keep up with the suspensions and horsepower of the vehicles they are used on. To get the latest trends and to understand the technologies involved in everything from racing, UTV, and enthusiast off-road tires, we spoke with some of the top tire manufacturers including, Peter Calhoun, Motorsports Marketing Manager at BFGoodrich Tires, Cameron Parsons, Product Manager, Competition & Specialty Tires at Toyo Tire U.S.A., Sean Kleinschuster, Director of Engineering at Tensor Tires, and Edwin Abd, Atturo Tires Team Racer. SJ: Over the decades, tire diameters have increased on race vehicles with many now sporting 40-inch diameters. What is the advantage of a larger diameter tire? X Peter Calhoun: In the simplest of examples– larger tire, smaller hole. A larger diameter tire allows you to smooth out the whoops and bumps for a faster overall pace. This can be an issue in some situations, because the vehicle must have the power to not affect acceleration. The vehicle also must have suspension clearance and travel to maximize the benefits. UTV evolution has seen a gradual increase in tire diameter in certain classes and disciplines. At the same time, it has put a strain on finding a weak link in the driveline. CVs, wheel bearings, or half-shafts are prime examples of components that have been tested by the growth of larger, heavier tires. Cameron Parsons: Going with larger diameter tires comes with a few advantages. One of the primary advantages is increased air volume, allowing for lower inflation pressures while still safely supporting the load of the vehicles. We are also seeing improved durability as larger diameter tires enable the vehicle to drive over rougher surfaces and larger objects. There are some other benefits with larger diameters, such as a greater contact patch for improved traction, as well as extra ground clearance. Edwin Abd: A larger tire diameter gives more ground clearance for racing through rocks, as well as keeping the axles up high in deep ruts when in the desert. Sean Klienschuster: The age-old adage of “the larger the tire the smaller the desert” generally claims that a larger tire will help you conquer more difficult terrain with fewer challenges. While larger tires can make it easier to pass over obstacles by increasing ground clearance and having a larger rolling radius simply using larger tires on your vehicle will not always make you faster. Tire size and weight need to be considered as attributes of the entire vehicle package when trying to improve the performance of a vehicle. Tensor focuses on making the lightest and most durable tires in the sizes we manufacture. We are steadfast in minimizing mass and un-sprung weight as one of the most important attributes of our tires and their ability to improve vehicle performance. SJ: Are off-road race tires made with various tread designs and rubber compounds for various terrain? For example, would a tire made for a state-side race also be the same for Baja? Calhoun: The modern radial tire is a very complex and finely tuned component of any vehicle application. The tread design and compound are two of many variables which help define the ultimate performance, longevity, and toughness of a tire, whether it’s for the street or competition. Tire design for off-road racing presents another variable due to the variety of racecourses. The courses have a variety of terrain to start with, but one that is in a constant state of change. BFGoodrich tire’s toughness is credited to years of experience around the globe in many forms of off-pavement racing. These races would include desert, cross-country rally, stage rally, and rock climbing. Parsons: We definitely take the different terrains under consideration when developing our race tires. The Open Country M/T-R was tested with different trucks, drivers, and surfaces both stateside and in Mexico. Different tread designs and rubber compounds would surely benefit performance if specialized for different surfaces and environments. This stresses the importance of building a tire that can handle them all. This is especially important for some of the races, such as SCORE events, that send trucks over sand, volcanic rocks, mud, soft dirt, and more. Abd: Yes, different tread designs and compounds are used for different environments. The spread of tread designs helps racers to match their tire to the terrain over which course they will run. With our tires, however, what the racers use for the competition are the exact same tires a customer can use on their personal vehicles, with the exception of our new off-road only softer compound Trail Blade Boss Green Label. Are state-side race tires also the same for Baja? In our experience, racers have used the same tires state-side and in Baja. Although, we have noticed that short course racing and Baja style racing usually use a more aggressive all-terrain style tread per se, with a harder compound which makes it easier to slide and spin tires, but still a hard enough compound to where they last. When in rocks the tires generally require a softer compound with a more aggressive tread design with a focus on the low-speed grip. Klienschuster: Tensor has two tread designs currently in our competition tire offerings. The DS was our original design and is a more open tread concept. The DS tire is best suited to softer surfaces like sand and mud. Our DSR tread design has more tread elements and less void space. The DSR is best suited for loose over hard surfaces typical of mixed desert terrain and fire or ranch-type roads. We offer multiple compounds that provide different performance characteristics. Our standard “Hard” compound provides a balanced mix of wear and performance. Our optional “Soft” compound will wear more rapidly but provide greater performance during its shorter usable life. SJ: Lately, wheel diameters for race tires have also increased. What advantages do 18-inch diameter wheel sizes have for race vehicles? Abd: Generally speaking, Baja and Ultra 4 are running a 17” wheel. Some rock bouncers running 44” + tires are running 20” wheels. But generally, 17” is the go-to for off-road bead lock wheel size. In general, larger diameter wheels may provide several advantages. These include accommodating a larger brake system, additional clearance around the brakes, and in some higher speed applications, the shorter sidewall may have some advantages in handling. Klienschuster: The current effort to increase wheel size has two main goals. The first is increasing brake system clearance to utilize larger calipers and rotors. Vehicles have more power than ever before combined more frequently with all-wheel drive drivetrains and the latest suspension technology. This means racers are going faster than they ever have before. Stopping vehicles that are going faster and using larger tires means that brake systems need larger components to survive the demands put upon them. The second is reducing the sidewall height or aspect ratio which increases the cornering stiffness of a tire. Cornering stiffness is basically a measure of how much cornering force a tire generates per degree of steering input. The higher the cornering stiffness the sooner the tire will develop cornering force. This translates to the driver as more responsive steering. SJ: Off-road enthusiasts usually lower tire pressures for greater traction over rocks. What kinds of tire pressures do off-road racers use on their tires, and is it different for vehicle types and terrain? Calhoun: Tire pressure is the key tire performance variable for both grip, durability, and ride comfort. The range of pressures varies greatly due to vehicle type, tire size, and terrain to name a few. BFGoodrich, in partnership with Michelin subsidiary Teleflow, is in the process of introducing a Central Tire Inflation System (CTIS) to the off-road racing and recreational market. Under the brand name BFGoodrich ActiveAir®, this will allow vehicles to air-up or air-down without exiting the vehicle. It has the ability to automatically pre-program GPS coordinates, and the CTIS technology has been tested in Dakar Rally competition, military, and commercial applications. Parsons: It all depends on the vehicle and how it’s going to be driven. Enthusiasts commonly lower inflation pressures for extra traction and sometimes for a softer ride. Especially when driving on tight bumpy trails, users will lower pressures significantly. However, a tire’s load capacity must always be considered when adjusting inflation pressures. This is a serious factor, especially in racing, where vehicles are driving at high speeds and experiencing varying loads with jumps. We aim to keep pressures low enough to maintain traction and smooth out the ride while ensuring that there is enough pressure to maintain load carrying capacity for the vehicle and driving conditions. Abd: Off-road racing vehicles use fairly high tire pressures to keep the tire from peeling off the wheel when sliding into a turn, as well as help deflect rocks from the sidewalls and stop the wheel from pinching a sidewall. Depending on the tire and size, 37-40” tires are fairly common to see pressures as high as 28psi, and as low as 18psi, depending on the amount of rock and sand on the course. A mixture of the two, like KOH, would use medium air pressure around 22-24psi. Klienschuster: Optimal tire pressure depends on the following factors: vehicle weight and weight distribution, tire size, terrain, and driver preference. Tire pressure is one of the most effective and basic ways to alter the handling and performance of a vehicle and must be checked before every use. Generally, you will want to have just enough inflation pressure to support the weight of the vehicle and protect the wheel from damage. We provide our racers with a guide of starting inflation pressures for each of our tires and a range of vehicle weights. They can then tune from the starting pressure to find what works best for their vehicle and preferences. SJ: With more AWD vehicles appearing in both SCORE Trophy Truck and Class 1, does this affect the types of tire design, overall wear, weight, etc? Calhoun: The growing popularity of AWD trucks in Trophy Truck and rare exception Class 1 presents different challenges and potential tire solutions. AWD allows the balanced delivery of power to all four corners. This aids acceleration, but also tire wear. Combined with the increased horsepower, the AWD truck’s speed per kilometer can be faster than a traditional 2WD truck under identical conditions. Parsons: As you might expect, distributing the power distribution from just the rear wheels to all four wheels makes a big difference. This takes some stress away from the rear tires and adds to the front, overall extending tire life. AWD systems add extra weight to the overall vehicle, so it does call for changes that increase load capacity. Klienschuster: AWD vehicles will generally distribute tire wear more evenly to each corner of the car. Compared to a RWD vehicle, an AWD vehicle will wear front tires slightly faster and rears will wear slower. We do not specifically design tires based on drivetrain configuration. SJ: SCORE Fans like to imitate what the racers are doing, so for a vehicle that will see daily on-road driving, but is also used off-road, what can they look for to get the best of both? Calhoun: For years, the BFGoodrich All-Terrain T/A KO2 or Mud-Terrain T/A KM3 have been class-leading examples within their respective categories. Both tires have race-proven pedigree, including class-winning performances in Baja, enabling our brand to have the tire sidewalls engraved “Baja Champion.” For BFGoodrich, this is not a marketing slogan, but an integral part of the tire’s design and development to prove the performance a consumer should experience. The BFGoodrich Trail-Terrain T/A® launched in 2021 offers additional road comfort with light off-road capability for small to mid-size trucks, CUVs, and SUVs. Parsons: We love seeing enthusiasts build out their vehicles in a similar fashion to the racers’ trucks. What’s even better, is that the Open Country M/T is used on many racing vehicles and is available to the public. That being said, the SCORE race trucks are very fast, powerful, and heavy. A vast majority of enthusiasts have no need and might even see reduced performance if they ran the same tire sizes as the race trucks. 32” to 37” tires should serve most enthusiasts, depending on how aggressive they want their setup to be. Some of the more serious enthusiasts may choose to go up 40” to be more off-road capable, and Toyo is actually one of the few manufacturers to offer this size for vehicles driven on the street. In this size range, users can choose between options such as the Open Country M/T, R/T, and A/T III to find the best suit for their balance of on and off-road usage. Abd: For the non-competing enthusiast who admires the off-road “look,” they may benefit more – especially for a daily driver – by choosing a tried-and-true Atturo product closer to the traditional M/T or MTS (Mud Terrain), A/T, or ATS (All-Terrain). If the enthusiast’s vehicle is also enjoyed by the family, they should check out the hybrid Trail Blade X/T, designed for the rigors of the urban terrain. SJ: With UTVs becoming more popular in off-road racing, and with their abilities and speeds increasing, are tire manufacturers keeping up with the demand? What can UTV racers and enthusiasts expect to see in the future? Calhoun: BFGoodrich was the first major tire brand to offer a UTV specific race tire with the introduction of the Baja T/A KR2 in 2015. Since then, additional sizes have been launched. Our new All-Terrain T/A KDR3, which is developed in cooperation with Red Bull OT3 for Dakar and FIA Cross-Country Rally, will be suitable for North American desert racing on certain terrains. At Dakar 2022, the KDR3 won all 13 stages in the T3 class led by American Seth Quintero’s 12 stage wins. Parsons: The UTV market has been booming among enthusiasts, and the motorsports market has been pushing innovation for these vehicles. We see these vehicles quickly becoming faster and more powerful, and the sub-30-inch tires that many ship with may not satisfy the needs of the consumer. Toyo Tires kicked off its Open Country SxS product line with more aggressive sizing in 32- and 35-inch sizing to stay ahead of the demand. Users are frequently pushing the limits of these vehicles, so tires tend to be among the first upgrades, alongside power adders. The factor that users need to consider is their drivetrain setup. Bigger tires mean extra weight, adding stress to the clutch. On the other end, you want to be sure that as the vehicle gets faster or as you push it harder, you’ve improved the traction ability to keep it safely under control. So, users need to make sure to account for components of the entire vehicle before they upgrade any single item. Abd: More UTV tires are being made in larger sizes with different tread designs than stock that can be used in multiple terrains. There is a trend toward tires following a similar design as regular Light Truck (LT) tread patterns. The construction of UTV tires is also evolving to be more similar to the on-road tires to better withstand the speed, power, and weight of these Klienschuster: Tensor leads the market in competition UTV tire offerings. We were the first to offer a true 33-in diameter competition tire which is currently the go-to option for top racers. We have the lightest 35in buggy tire in the market perfectly suited for when rule books begin allowing that size on UTVs. We continue to evolve our products and innovate in the UTV space based on racer feedback and controlled testing. Tensor’s 37-inch tires are widely used in a variety of UTV and other classes SJ: When it comes to off-road tires, most talk about traction, but how important is sidewall construction when it comes to puncture resistance, load carrying capabilities, and handling? Parsons: Durability is a major factor in off-road tires that too many people overlook. High speeds and excellent handling are often the highlights of the discussion, but a damaged or punctured tire can ruin a race or off-roading vacation. The sidewall takes a lot of punishment as it continuously flexes and changes shape as the vehicle drives over objects, jumps, or as it takes turns. Further, it’s very common to slide the vehicle sideways, forcing the sidewall of a tire perpendicularly into rocks and debris. A lot of development goes into strengthening the sidewall to better handle load stress and fight against punctures. BFGoodrich’s 40-inch KR3s are now being used in Class 1 vehicles because of their durable sidewall and traction capabilities X Abd: Sidewall construction is KEY to an off-road race tire. Every sort of off-road racing, with the exception of short course dirt track racing, sees rocks and other debris that can easily tear through a sidewall. Short course racing puts high stress on sidewalls with the jumps. Even with the best tread design, if you have a poorly constructed sidewall that doesn’t hold, the tire does you no good. Load-carrying capabilities are not as relevant for off-road race tires since the goal is to go fast and far while supporting the weight of the vehicle. If the sidewall can hold up against any terrain you throw at it, it is easier to be more comfortable and confident with handling knowing you won’t blow a tire. This is why the Atturo Trail Blade BOSS has an overbuilt sidewall with extra-thick rubber. The Trail Blade M/T and X/T both have 3-ply sidewall construction to withstand the hard landings from short course jumps. Klienschuster: A durable tire is very important. We have a patented rib design feature on our tires in the upper sidewall. It is there specifically to provide puncture and cut resistance in that susceptible region of the tire. With how close races are these days a single flat can be the difference between a win and being outside the top 5. Multiple flats typically mean you are nowhere near contending in the event. The carcass and belt materials we use in our competition tires are selected for their high strength but low weight. We do extensive testing to evaluate different materials and construction specifications to optimize the traction, durability, and handling of our tires. SJ: What are the best and most affordable routes for racers to take in order to get premium off-road racing tires for competition? Calhoun: BFGoodrich has a nationwide network of authorized dealers, but racing tires remain exclusive to Jackson Motorsports Group (JMG), Off-Road Warehouse (ORW), and Tersa Llantas in Baja California, Mexico. Parsons: Toyo Tires has a network of dealers that sell the same Open Country tires that many of our pro drivers race on. These dealers can be found at the Toyo Tires website. Interested drivers can also visit to learn more about support programs and sponsorship programs. Klienschuster: We offer a racer program that provides discounts on products and eligibility to participate in new product R&D testing. Visit our website for more information. Abd: The first thing they should do is check if there is an Atturo tire for their vehicle and class! Then, look for a racer program where tires are offered to racers at a discounted price. Atturo’s Trail Boss MT race tire is derived from extensive off-road racing testing SJ: As a tire manufacturer, how does the company support racers using your tires? Calhoun: SCORE has been an important part of BFGoodrich’s legacy for over 45 years. We continue to offer on-site technical support at each event from full-time engineers, as well as mapping and pit support services. These two services, both long-standing BFG traditions, are going through a transitional phase in 2022 driven by the changes in technology and the business environment. BFG will now have a nominal fee for the map book and pit service but remain significantly less expensive than other providers. Parsons: Toyo Tires has a network of dealers that sell the same Open Country tires that many of our pro drivers race on. These dealers can be found at the Toyo Tires website. Interested drivers can also visit to learn more about support programs and sponsorship programs. Abd: Atturo supports our racers with priority access to new tires, discounted pricing, and helping create great marketing content for social channels and mutual promotion. Just as important, we look to our racers for feedback on the tire performance and help with promoting the Atturo brand and racing success. Klienschuster: We offer a racer program that provides discounts on products and eligibility to participate in new product R&D testing. Visit our website for more information.

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