Best forParents looking for a narrow convertible car seat to fit up to 3 across in a single row
Top BenefitsCan be used from 5 to 120 lbs., high-quality frame and materials, can fit 3 across the rear seat of many mid-size vehicles
ConsiderationsHeavy, rethreading required to adjust height of harness shoulder straps, may not fit in all vehicles at the infant recline angle
Bottom lineThe Diono Radian rXT is a well-made convertible car seat that kids can use until they hit 120 pounds or reach the height restrictions. UAS connectors offer the easiest installation, and the machine-washable and dryer-safe seat cover make cleaning a breeze.
Looking for a narrow car seat that isn't going to eat into the middle seat's space—one that might even let you fit three across a single row of seats? The Diono Radian rXT is a good bet. This convertible car seat is designed to be suitable for kids from five to 120 pounds, and with a 10-year expiration date, it will have you covered for a good long while.
Our parent testers’ overall experiences installing this car seat ranged from very easy to somewhat difficult, which isn’t surprising—different cars present different challenges, and there isn't a car seat on the market that works in every vehicle. A good user manual is always a big help, and Diono Radian rXT's is easy to follow and well-organized, with helpful pictures and checklists.
Editors and testers had no problems attaching the UAS connectors to the anchors in their vehicles (detaching them was easy, too). But once the UAS connectors are attached, the real work begins. The challenge is getting the belt tight enough that the car seat can't be moved more than an inch in any direction when you tug on the base at the belt path. In our lab installations, getting the seat secure took some work, but it still felt easier than most of the seats we tried. The level of difficulty you encounter will depend on your vehicle, your strength and, frankly, your patience. While none of our parent testers found it difficult to position the seat at the correct angle, most of them had to move their vehicle's front seat forward quite a lot to accommodate a rear-facing installation. Of course, that's going to vary from vehicle to vehicle, but it's something to consider for long-legged parents.
To achieve a safe recline angle, the Diono Radian rXT has a detachable base, which is secured with a metal lock, and the curved foot of this base slides in between the back rest and seat cushion for a secure fit. Diono does not allow the use of a rolled towel or pool noodle to adjust the angle, so if you can't get the angle right with the detachable base, the car seat is incompatible with your vehicle. It's worth noting that Diono offers a foam angle adjuster, but it can only be used in the more upright rear-facing position, once your child has complete head control and can sit unassisted. The benefit of the angle adjuster is it can give you a bit more clearance between the car seat and the front row seat—super helpful as the rXT is one of the taller car seats on the market.
When your child is ready to sit forward-facing, the detachable base needs to be removed before installation. You can adjust the forward-facing recline by pulling an adjustment bar (located under the seat) upwards to lower or raise the seat bottom. If your child is riding forward-facing but is under 40 pounds, you'll also need to use Diono's "SafeStop" device, which attaches to the harness straps on the back of the seat and is designed to absorb energy and reduce impact for smaller kids.
If you need to secure this car seat with your vehicle's seat belt rather than the UAS connectors, it's possible, but it may be a bit more challenging in some cars. Threading the vehicle's seat belt through the appropriate belt path is simple enough, but tightening it can be difficult because the belt-path on Diono car seats is low on the base and your vehicle's seat belt buckle may interfere with a tight fit. In some vehicles (like the one we tested this car seat in), you can twist the vehicle's buckle to shorten it before clicking the seatbelt in, which keeps the buckle from coming in contact with the belt path on the car seat. But some car makers prohibit this—you'll need to check your vehicle's manual.
The Diono Radian rXT has to be installed in vehicles with auto-locking belts or with a locking clip. To engage the auto-lock, you need to pull the seat belt all the way out and then slowly let it retract; our editors found it can be a bit tricky to ensure the belt doesn’t twist as you do this, but it's so important for keeping your child safe in a crash as twists can add stress points, making the bely more likely as secure as a flat-lying belt.
Forward-facing installations require you to attach the car seat's tether strap to the tether anchor on the back of, or behind, the vehicle's seat. During testing, our editors found adjusting the length of the tether can be somewhat awkward in some vehicles, but to make it easier to tighten the strap, you can loosen and attach it to the car's anchor before attaching the UAS clips.
You can use the tether in rear-facing installations, but only if your vehicle has the appropriate anchor in front of the seat the Diono car seat is being installed in. (If you're not sure whether your vehicle has this or if the anchor is appropriate for car seat installations, see your vehicle's manual or call the manufacturer.) You'll need to purchase a D-ring tether connector strap to install the top tether in the rear-facing mode.
The Diono Radian rXT is no lightweight thanks to a full steel frame and aluminum-reinforced side walls and headrest, which are meant to add strength. In fact, at 31 pounds, the Radian rXT is one of the heaviest convertible car seats we tested, so it's best used as a "set-it-and-forget-it" seat (no moving it back and forth between vehicles). It is, however, narrower than most car seats: at 17 inches wide, three can fit across the rear row of seats in many mid-sized vehicles. Height-wise, the Radian rXT 28.5 inches tall, and the majority of our parent testers to move their passenger seat forward a lot when installing it rear-facing.
Our testers all agreed the Diono Radian rXT's five-point harness is easy to use, and our editors felt the same way. Clips are easy to fasten and release, and we particularly appreciate the ratchet-like tightening feature for securing the harness against your child. The crotch strap is padded, as are the shoulder straps, which also have a non-slip texture on the back. The majority of our parent testers strongly agreed the harness felt secure, and all of them said the straps sat comfortably against their child's body.
As your child grows and the shoulder strap height needs to be adjusted, you'll have to spend some time rethreading it. Editors found this process simple and straightforward, and parents who adjusted the harness height during testing told us it was mostly easy. However, it does mean that you have to make the adjustment prior to installing—something you don't have to do with car seats that allow you to adjust harness height without rethreading. (It's worth noting that you have to rethread the harness for the infant harness levels on any convertible car seat—none are totally free of manual adjustment.)
As mentioned above, the harness features Diono's "SafeStop" design, which, in the event of an accident, minimizes the force against the head, neck and chest of smaller children (under 40 pounds) who are riding forward-facing.
The full steel frame of the Diono Radian rXT is undeniably sturdy. The headrest and side walls are also reinforced with aluminum, and the seat is padded with energy-absorbing EPS foam—all features meant to keep your child safe. Plus, the seat fabric is soft and smooth for coziness. Our parent testers all strongly agreed the Diono Radian rXT has a high-quality frame and fabric. Of course, fabric only stays nice for so long. When the inevitable messes happen, the seat can be spot-cleaned easily with a bit of mild soap and water. And when really big messes happen, the seat cover can be completely removed and thrown in the wash in under a minute, and it's dryer-safe, too.
The majority of our parent testers told us their little one was comfortable in this car seat, and it's pretty easy to see why. The Diono Radian rXT has a narrow profile and may not look as plush as some other car seats, but memory foam padding makes for a comfortable ride. The head support can be moved up and down (it can be a bit stiff, though), but it's worth keeping in mind that even in the most reclined position, the seat sits quite upright when it's installed forward-facing, so a napping toddler's head might fall forward if they're not leaning against the side walls. The seat also features expandable sides, so it can become roomier as your kiddo grows, as well as a removable cup holder to keep drinks, snacks or even a small toy handy.
The Diono Radian rXT is one substantial convertible car seat. Our editors appreciate that it can accommodate kids up to 120 pounds, and they were impressed with the compact width that allows for three of these car seats to be installed in a single row of seating in some vehicles. Parents who tested this car seat described the overall quality as good or very good, and the majority said it was easy to use. While their views on value ranged from average to very good, all agreed the Radian rXT is worthy of the Today's Parent Approved seal. If you're looking for a high-quality car seat that'll have you covered for the long haul, the Diono Radian rXT is a smart choice.