Thule Motion 3 XL vs Yakima SkyBox NX 18: Which 18 cu ft Cargo Box Fits Your Garage and Skis?

On paper the two shells are near twins. Thule lists the Motion 3 XL at 84.7 x 35 x 17 in outside; Yakima lists the SkyBox NX 18 at 84 x 36 x 16.5 in. Half an inch of height goes to the Yakima, an inch of width to the Thule, and neither changes whether a garage door clears the box. What matters is box plus crossbars plus roof. If a 16.5 in shell on your rack is already too much, the answer is not the Thule but a low box such as the Motion 3 XL Low, which drops to 14 in and gives up capacity to do it.

Both boxes are about 7 ft long and meant to sit forward so the tailgate can swing; Thule specifies just over 52 in of clearance ahead of the hatch.

Inside, Thule gives 80 x 29 x 15 in; Rack Warehouse lists the Yakima's usable floor at 77 x 27.5 in. The Thule wins on paper, but BetterTrail's loading tests point the other way: the Yakima's clamps sit low and leave a flat floor, while the Thule's hardware bulges into the load space and sometimes forces long flat items to be shuffled.

Thule rates the Motion 3 XL for skis up to 200 cm, 5 to 7 pairs, or 3 to 5 snowboards. Yakima rates the SkyBox NX 18 for skis up to 195 cm. For recreational skiers on 165 to 185 cm boards the difference is academic; for a tall skier on 195 cm or longer skis, the Thule's 5 cm is the safer margin.

In BetterTrail's identical test load, both boxes took three pairs of 177 to 182 cm adult skis, poles, and two pairs of children's skis. Both have molded tie-down points; the Thule adds a reach strap for closing the lid from the ground.

This is the clearest mechanical difference. Thule's PowerClick clamps have a torque indicator built into each dial: turn until it clicks and the clamp is at spec, with nothing separate to lose. Yakima's clamps are tightened with a removable torque wrench that clicks three times and then comes out of the box. BetterTrail found PowerClick easier to center over the bars and quicker to operate, and both BetterTrail and OutdoorGearLab call the Yakima's tool easy to misplace. OutdoorGearLab rated the Thule's ease of use 8.8 of 10, best of the eight boxes it tested.

Crossbar spread goes to the Yakima. Its product page gives 24 to 40 in, which covers most factory rails, aero bars and wide-set aftermarket setups. Thule does not publish a range for the Motion 3 XL; BetterTrail measured the clamps at 21 13/16 to 36 5/8 in. Bars more than about 36 in apart rule out the Thule; bars closer than 24 in rule out the Yakima. Measure before ordering.

The Thule's SlideLock lid is the reason people pay the premium. It lifts with one hand from either side, the handle shows red until the lid is fully latched, and the key cannot be pulled until the box is shut. BetterTrail calls it one of the simplest locking systems it has used; GearJunkie notes the handle is reachable from the ground on a tall SUV. The Yakima's metal handle needs a firmer push to release, per BetterTrail, and OutdoorGearLab found its closed indicator less foolproof. The Thule also opens 2 in higher, 14 in against 12 in by BetterTrail's tape, the difference between sliding a cooler under the lid and lifting it over.

Neither lid is flawless: BetterTrail found the Thule's latch finicky when the box is moderately full, sometimes needing a press at all three latch points, and Switchback Travel found the same hardware stiffer in cold weather on the Low version.

On noise, BetterTrail describes the Motion 3 XL as stable on the highway with minimal wind noise, while Switchback Travel lists road noise compared with sleeker designs as the Yakima's main weakness, blaming its blunter nose. Neither measured decibels; vehicle shape and crossbar type usually matter more.

Manufacturer figures and scales disagree. Thule claims 51 lb and Yakima 53 lb, but on BetterTrail's scale the Thule came in at 55 lb 14 oz and the Yakima at 50 lb 8 oz; OutdoorGearLab weighed both at 51 lb. Call it a tie; either is a two-person lift onto a tall roof.

Finish is a genuine split. The Thule's glossy black or Titan paint looks like a car panel and scratches like one; BetterTrail saw small marks after five reinstallations, and OutdoorGearLab flags the scuffing. The Yakima's NX nano-texture hides dirt and marks, which OutdoorGearLab prefers. Both carry a limited lifetime warranty that excludes wear and scratches, and both are made in the USA, so neither point tips the decision.

Buy the Thule Motion 3 XL if the box lives on the car all winter and gets opened most weekends, if you carry skis at 200 cm, or if your crossbars sit closer than 24 in apart. The PowerClick mounts, one-hand lid and taller opening stop mattering on one trip a year and never stop mattering on twenty. It sits in the top price class, and its paint will show the years.

Buy the Yakima SkyBox NX 18 if you want the same 18 cu ft, load limit and warranty a price class down, if your crossbars are more than 36 in apart, or if a scuff-hiding finish is worth more to you than a glossy one. Keep the torque wrench in the glovebox and accept a firmer latch and a little more road noise.

Both are in our rooftop cargo box guide, where the Yakima is the overall pick and the Thule the premium one. If your garage is the real problem, neither is the answer; look at the low-profile boxes there instead.