Ready For Big Tires?
First things first: big tires are amazing. There will always be arguments from the naysayers that to justify them, you'd better be operating on some really rough landing zones. But if the cost isn't a huge factor, then why not? The pros far outweigh the cons. Upgrading to big tires like Alaskan Bushwheels can really open up your available LZs. They make a huge difference in rough surface performance, whether it's out in the backcountry or the makeshift dirt/clumpgrass strip parallel to the paved runway at your local municipal airport.
The cool appearance has sold more Bushwheels than any other motivating factor. We all readily admit this is 80% the reason we want them, even if the practical need isn't truly there. But in addition to that tougher bush plane look, the tangibles are tough to deny: big tires (26" diameter and larger) provide better prop clearance, higher angle-of-attack for slower takeoffs and landings, reduced airframe impact on rough surfaces, and the best one of all—opening up LZs where smaller tires just can't (or shouldn't) go.
But with those gains come trade-offs: reduced braking power, reduced cruise speed, and even shorter wear life on soft compound rubber of Bushwheels, to name a few. What should an aircraft owner know about running big tires before making the leap? Here's what pilots from our forum have learned from first-hand experience.
A note for the tricycle pilots: Much of the info below applies to nosewheel aircraft, too. Obviously main tire size selection is more limited, and we don't cover nosewheel fork upgrades. But trikes have always had a shortfield advantage in achievable takeoff AOA.
1 Bigger Tires = Different Braking
"With the 31s I have to press the brakes much harder to prevent the plane from moving. You can just feel the brakes don't have the same 'effectiveness' as before."
Bigger tires, bigger brakes. Nose-over?
Bigger tires require bigger brakes. Larger diameter tires increase the rolling circumference, which reduces the mechanical leverage your brakes have using the same little discs. That means longer stopping distances, especially when heavy. Pilots upgrading from 8.50s to 29s or 31s often notice a softer brake feel and need to recalibrate their stopping expectations. Expect to use more pedal force and plan for longer rollout distances. Tail-up taxiing may prove even more challenging than before.
If your aircraft has single-piston brake calipers, AKA "single puck," you will need to upgrade to double puck brakes. Anticipate an extra $1,500-2,000 depending on brand for new calipers and appropriate STC if needed. The Approved Model List (AML) on the Alaskan Bushwheels STC requires "heavy duty brakes" for some aircraft model and tire combos.
2 Speed and Fuel Burn Penalty
"I lost 7 to 8 knots going from 8.50's to 29's on two different 185s. Adds up burning 15+ gph. Fun factor is out of this world."
C185 cruise speed w/ bushwheels
Bigger tires weigh more and create more drag—not just by being big, but from the aerodynamic penalty of what is essentially a round cross-section. Even a 3–5 knot loss adds up over long cross-country legs, so match your setup to your typical mission. Sometimes having a second set of wheels paired with 8.00 or 8.50s is a good solution for long XC where off-airport landings aren't planned.
31 inch Bushwheels on a Cessna 170B—Kenai, Alaska. Takes a little of the risk out of landing smooth sandy beaches.
3 Brake Clearance and Tire Pressure
"When I put bigger rubber on my Maule I had to put a factory spacer kit on. 1/16" is not enough. I now have 1/4" and it never touches."
Brake caliper/tire clearance
Brake caliper clearance from the inner sidewall can get tight when installing ABWs or similar large tires, they're just wider in addition to larger diameter. Always check your calipers and lines for rubbing, especially if you're using adapters or older wheel setups. Lathing through the sidewall of your new $4,000 tires is bad in multiple ways. The manufacturer usually sells spacer kits which stand the wheel farther from the gear leg, creating space betwen the tire and caliper.
Proper tire inflation also affects clearance and handling—underinflation can cause rubbing, while overinflation can make landings rougher strips. Measure your brake clearance after installation and verify line routing before your first flight. Bushwheels should be run at fairly low pressure to get their full benefit. The installation docs say minimum of 8 PSI, but 4-6 PSI is where the real baby-head sized rocks are easily absorbed.
Speaking of tire pressure, you might ask where you get inner tubes this size? Psych! Bushwheels are a tubeless design, in fact they are a fully sealed toroid with the valve built into the sidewall of the tire. Other brands of big tire like the Desser 31x10 can be run tubeless in a more conventional sense using sealant and special sealed wheel halves from Grove.
4 Tire and Brake Compatibility
"Another thing you have to remember when spacing the disc farther from the tire and rim is that the pins that hold the caliper are long enough."
Desser 8.50x6
To follow on the last point, not all brake kits and wheels are designed for larger tires. Certain setups require spacers or different torque plates. The pins that the calipers float on have to be long enough to accommodate whatever standoff is required. Before upgrading, check your wheel and brake model numbers and confirm compatibility—especially if you're mixing components from different manufacturers, like original Cleveland with ABI matching models. Sometimes you just have to factor the cost of brake upgrade into the tire upgrade.
5 Tire Wear and Maintenance
"‘Flight hours' is not a good measurement for tire wear...it's all about the number of landings, taxi distance, runway surface, etc.. If the aircraft tracks straight, I wouldn't worry about alignment. That said, all my tires wear from the outside in, since it's the outside of the tire that scrubs on touchdown."
8.5 X 6 tire wear and tear
Bush tires, specifically soft-compound Bushwheels, wear differently than standard 8.50s or even Goodyear 26s. Pavement accelerates wear dramatically, and heavier aircraft see faster tread loss as touchdown with a non-rotating tire on a hard surface is akin to road rash. Taxiing and using differential braking also grind away at the rubber. Keep a close eye on wear patterns—pavement and heavy loads will eat through that soft tread faster than you'd think. There's always the bedliner trick...
Sibling Bearhawks parked at Moose Creek, Idaho—Red/white is wearing 29s and the blue/white 35s.
6 Angle of Attack: Prop Clearance & Ground Roll Differences
"Bush Wheels hide a lot of my poor landings!! You will feel a bit more drag when you touch down but after a few landings you don't notice it. Much softer landings with less bounce. Tire Pressure makes a difference. Get them down to 3 psi and they roll a lot harder around the hanger. Pump them up and they roll easier but not as soft a landing."
Bigger Tires — What to Watch For?
Larger tires at low pressure increase ground contact and rolling resistance—theoretically increasing takeoff distance—but the countering advantage is that they allow you to present a higher AOA in the three-point attitude on the ground. With adequate power that equates to shorter takeoffs. This also has the benefit of greater prop ground clearance.
The final consideration for greater AOA is the site picture over the nose while on the ground. It can really take getting used to, and forces you to adopt some good old peripheral vision techniques and sometimes S-turns while taxiing to verify a clear path ahead. Anticipate minor changes in ground roll and adjust your technique accordingly.
7 Suspension / Gear Loads (Heavier Tires → Struts/Axles)
"You've effectively hung heavier weights at the end of your gear legs, preloading them more than your old small tires. Any little fluctuation in wing loading causes a nice well-balanced oscillation. I think the only solution is stiffer gear legs, but I'm not sure what your options are for a 206."
Big, soft and bouncy
Big, soft, and bouncy heavy tires put additional stress on landing gear and suspension components. For the two main gear designs—steel spring gear like a Cessna, and A-arm oleo strut style like a Super Cub—this can manifest in different ways. The larger radius of the big tire equates to a longer lever, applying amplified force to the gear. In a hard side-loading event, like heavy crosswind touchdown, this can apply forces to weak points in the structure. It's one of the reasons you often see Super Cubs on 35s equipped with safety cables for the event that bungees/shocks or the cabane vee fails. On a Cessna, those forces can be transferred into the gear box in the fuselage, so it had better be strong. That's why the PPonk "Beef Up" kits exist.
Over time and rough landings, added force can lead to increased wear or need for maintenance. Annual inspection should check for smoking or popped rivets in the gearbox, or cracking in A-arm steel tube gear legs and struts.
Bonus: Before upgrading, check out the Tire Guide, which includes tire specs, setups, and pilot tips in one place. It's a great reference if you're comparing dimensions, wheel sizes, STCs/applicability to type, or just surfing for ideas.
Big tires aren't just for taildraggers. This Cessna 336 Skymaster has some rough places to go. How tough are those gearboxes?
