TIRE-SIZE COMPARISON: 28″ vs. 30″ vs. 32″ TIRES
New or different tire sizes are one of the most popular mods that UTV and ATV owners make to their machines. The current style is massive tires for off-road trucks, and that trend has leached into UTV and ATV culture as well. But, monster tires can ruin a truck’s performance and handling, and we all have to make sure we don’t just change tires to make our quad or UTV look cool. We should choose tires that work the best rather than those that look the meanest. That point was driven home last month when Ed Teixeira showed off his Yamaha YXZ1000R UTV with 26-inch tires on it—1-inch smaller than stock. It was a ball to drive, and it cornered like a lizard on a hot rock.
We have driven machines that had tires so big or so heavy that the UTVs were severely compromised. One RZR 1000 had tires and wheels that weighed 88 pounds each. That is close to the weight of all four of the stock tires. The machine had a high-performance engine and modified suspension but was far less impressive than a high-mile stocker we had along.
Now we have sport UTVs that come stock with 27-, 28-, 29-, 30- and even 32-inch tires. The question is, how do you decide what tires you should put on your machine? And, how do you choose? First, you must decide what kind of riding you do most. What is most important when tackling the terrain you and your machine traverse? Optimal desert tires and rowdy mud tires couldn’t look more different. If you have a sport utility machine, you need to be concerned with load ratings. You may need to give up a little ride quality and perhaps even traction to get a tire that will carry the weight and allow a high-enough air pressure.
If your area has sections of deep mud that are critical to cross, you may be willing to put up with tires that are compromised and lumpy-feeling on packed dirt to ensure that you can plow through the muck efficiently. Likewise, a desert guy may give up traction in the sand to gain traction on packed dirt or rocks. If you have a lot of sand or loam soil without rocks, you will favor a tire that is light and hooks up rather than worry about tread that lasts forever.
We can’t help you with the tread pattern for your terrain except to suggest that open tread is good for soft or muddy terrain, and that closely spaced tread blocks and high-ply sidewalls are better for rocks and desert. But, we did want to do a comparison of common tire sizes that would remove as many variables as possible. You might be surprised at how few light, general-purpose tires there are out there available in multiple sizes. We wanted identical tires in 29-inch, 30-inch and 32-inch sizes. We found CST’s Dingo tires (that impressed us so much in last month’s issue) come in 28-, 30- and 32-inch sizes. We ordered those sizes and came up with three complete sets of stock Polaris wheels to keep everything even. The 28x9R14 Dingo costs $207 and weighs 27 pounds. The 30X10R14 runs for $216 and weighs 32 pounds. The 32X10R14 Dingo is notably larger, and it will set you back $229, but it weighs only 34 pounds. We thought that was very reasonable for such a large tire.
We mounted all three sets ourselves easily enough. Tires with taller sidewalls are generally easier to mount and seat than those with shorter sidewalls. We had to go to a tire shop to have the 28-inch tires seated on the stock Polaris rear rims. We kept all 12 tires set at 15 psi. We selected the awesome Polaris RZR Dynamix Turbo 4 for the majority of the testing, but we also used the 30- and 32-inch tires on the 72-inch-wide RZR Turbo S. The S comes with 32-inch tires on 15-inch wheels, and we tested 32-inch Dingo tires on 14-inch rims. They fit on the front but require trimming a plastic wiper on the rear for clearance.
We took both cars and all three sets of tires to the high desert where we have sandy, packed, rocky terrain in one area. We were also looking for some good hills that would load the engines to help us feel and measure comparative performance. With each tire swap we went directly to a straight uphill pipeline road for a timed, uphill sprint. We wanted the engine up to temp but the belt still relatively cool. We timed the sprint with full gas tanks.
After the sprint we drove a 20-mile loop over a variety of surfaces to get a feel for the different tires, then we swapped out the wheels as needed. We didn’t use the 28-inchers on the Turbo S to avoid clearance issues. We have been driving the Dynamix 4 with 30-inch tires and the Turbo S with 32-inch tires, so we started there. The four-seater provided no surprises. We like it on 30s. We know it could be better with clutching mods for the tires, but it was pulling them fine, so we left it for now.
The S felt a bit different. Dingo tires are rounder in profile than the stock tires, and we like that feel. With 14-inch rims and 32-inch tires on the Turbo S, you feel the added life of the taller sidewall, but handling is a shade less crisp. It wasn’t at all problematic. It did have a more compliant feel in rocks and on sharp-edged bumps.
Our first switch was from car to car, so we ended with 30s on the Turbo S and 32s on the Dynamix 4. On the S, the 30s have a little smaller footprint, so there is less traction in loose dirt, but the car is super responsive to throttle inputs. You feel the lower center of gravity, and the car is more responsive to steering inputs. We had no clearance problems in whoops. We thought that the 32s would make the Dynamix 4 sluggish. Certainly the 32s offered a lot of traction, and it was great through whoops and in the loose. It was amazing the difference in the feel of the 32s on a wide car that was built for them and the Dynamix 4 designed with 29-inch tires. Pushing the Dynamix 4 hard on tight trails felt like the front wanted to tuck. Also, the car didn’t feel as planted in fast sweepers.
Our last swap was to switch the Dynamix 4 to 28-inch tires. Obviously this was a huge change to go from 32s to the 28s. Again, we had no clearance issues. The engine response grew super snappy, and the car felt planted in turns and on cambers. With the shortest sidewalls, the feel on the ground was crisp compared to the other sizes. We can see why many of the cars are designed around 28-/29-inch tires.
We hear so much that tall or heavy tires will make a car sluggish. We didn’t really feel that too much. Perhaps if we had less power to play with we would have felt it more.
Our drag race test was a good grade, and we made the tests as consistent as possible. Here are the numbers:
RZR Turbo 4 Dynamix
28-inch tires 11.59
30-inch tires 11.34
32-inch tires 11.29
RZR Turbo S
30-inch tires 11.26
32-inch tires 11.72
The numbers for the acceleration test were half surprising. The Turbo S numbers are about what we expected, but the Dynamix 4 numbers were opposite from what we anticipated. The longer car drives out harder and is very planted and secure under acceleration. With the 28-inch tires we could feel the acceleration fall off before the finish line. Clutching would have helped, or a shorter run. The added traction of the 32s made a difference there.
Despite all of the “common knowledge” that taller tires make the car feel slow, we didn’t feel that. We have felt heavy tires have a negative effect, but we purposely searched for a tire that was fairly light. If obstacle clearance is an issue for your riding, then the 32-inch tires are for you, but make sure you change the clutching to handle them. For us, the handling was the most settled with the lower, smaller-diameter tires. The larger tires roll through whoops and bumps easily, and you can feel the difference.
There is an undeniable visual appeal to the largest tires that fit on the machine. For the Turbo S, the stock tire size was our favorite to drive with, but we felt the car was quicker on twisty trails with 30s. For the Dynamix 4, we like the 30-inch tires. It has the benefits of rolling over obstacles easier but without the tall feeling of the 32s. In fact, 30-inch tires seem like the sweet spot. Most sport UTVs come with 29-inch tires, and the jump to 30-inchers is small enough that most cars handle the difference fine, and you gain the added benefits of the larger tire’s ability to roll over trail imperfections.
While we appreciate the roll of the 32-inch tires, for most cars, they really need clutching changes and may affect cornering. Certainly the wider car was more at home with the 32-inch tires than our 64-inch car.
If you do any technical driving at all, change the clutching to match the tires you are using if you do choose to go with bigger tires. Unless all you care about is flat resistance, look for tires that are light, in addition to having a tread pattern and compound suited for your normal riding areas.
The good news is that the UTV and ATV tire market is hot, and you should be able to find a tire that will improve your riding or driving experience.