Diono Radian: Ideal for 3-Across and Narrow Seating Positions

Diono has introduced a new generation of convertible seats based on the previous Sunshine Kids Radian line. The main new feature of these carseats is that they can become highback booster seats—they’re now 3-in-1 (rear-facing, forward-facing, and booster). The Radian R-series, the R100, R120, and Radian RXT, all have basically the same shell design but features distinguish them from each other.

  Rear-Facing Weight Limits Forward-Facing Weight Limits Booster Weight Limits Features
R100 5-40 lbs. 20-65 lbs. 50-100 lbs.
R120 5-45 lbs. 20-80 lbs. 50-120 lbs.
  • added structural support for higher ff weight limit
  • infant support pillows
  • memory foam under bum
RXT 5-45 lbs. 20-80 lbs. 50-120 lbs.
  • added structural support for higher ff weight limit
  • infant support pillows
  • memory foam under bum
  • adjustable head wings
  • shoulder belt guide for booster use is attached to head wings


This review is for the Radian RXT model, which rear-faces from 5-45 lbs., becomes a forward-facing seat for 20-80 lbs., and can become a booster for 50-120 lbs.


  • Weight limits:
    • 5-45 lbs. rear-facing with at least 1.5” of carseat above the child’s head or total height of 44”
    • 20-80 lbs. forward-facing with a child less than 57” tall
    • 50-120 lbs. as a booster with a child less than 57” tall, but child’s shoulders must also be at or above the 4th set of harness slots
  • 5 harness slot positions on carseat: 9”, 10.5”, 12”, 15”, 17.5”
  • 3 buckle slots: 3.5”, 5.5”, 7”
  • 2 position recline for forward-facing only; must use recline base when rear-facing
  • Restraint weight: 26.5 lbs.
  • Outside width: approx. 17” at widest point at shoulders, 16.5” at widest point at thighs
  • Inside width: approx. 14” at widest point at shoulders, 14.5” at widest point at thighs



Features and Advantages

5-point Harness from 5-80 pounds: The 45 lbs. rear-facing weight limit is currently the highest on the U.S. market. The high 80 lbs. weight limit means that heavier children will be able to stay in the seat longer before moving to a booster. Here’s a pic of my 57 lbs. 9 yr old dd:


High Rear-Facing Weight and Height Limits: Even the largest toddlers (and preschoolers!) will be able to rear-face in this convertible for a long time with the 45 lbs. maximum rear-facing weight limit and tall shell. This falls in line with the revised policies of the American Academy of Pediatrics and NHTSA to keep children rear-facing to a minimum of age 2 and longer, if possible. The deep seat will give larger rear-facing children more leg room.

Radian RXT - stock photo

5 Harness Height Positions: The wide range of harness slot positions means that the RXT will fit most children comfortably throughout their use of the seat.

The harness height adjusts from the back of the seat. Each strap is removed from the metal splitter plate and rethreaded through the correct harness slot. Use the slots at or below the shoulders for rear-facing, above for forward-facing. Children whose shoulders are above the top harness slots, yet still weigh less than the maximum forward-facing harness weight limit, may continue to use the carseat. For those children, the tops of their ears must be below the top of the carseat.

Recline Adjustments: There are 2 recline positions for forward-facing only and the separate foot is used for recline when rear-facing. With the recline foot on the seat for rear-facing, there’s no way to adjust recline position on the carseat itself other than by trying some installation tricks. For forward-facing, the bottom of the seat can drop down in front thereby increasing recline a bit. This may help the carseat install better in some vehicles.


Harness Adjuster and Use: The front harness adjuster tightens the harness with a tug-tug-tug motion.

SuperLATCH: For Radians manufactured before March 2014, the following applies to you: in vehicles made after 2005, Diono claims that their SuperLATCH connectors can be used to the upper forward-facing weight limit. There is some discussion in the child passenger safety world if this is best practice concerning lower LATCH anchors in some vehicles; most vehicle manufacturers place weight limits of 40/48 lbs. on their lower anchors. Suffice it to say, if you have a newer vehicle and want to use SuperLATCH to its full weight limits, it’ll have to be what we call a “parental decision.”

For Radians manufactured on or after March 1, 2014: the LATCH connectors may be used to a maximum rear-facing weight limit of 35 lbs. When used forward-facing, the maximum weight limit for lower LATCH connector use is 40 lbs. Once your child reaches these weight limits, switch to using the vehicle seat belt for installation, regardless of when the vehicle was manufactured.

When the carseat is used as a booster, however, it may be LATCHed in at any weight. This is because the LATCH is simply holding the carseat to the vehicle while the seatbelt is restraining the child and will be the device taking crash forces.

There is an adjuster on one side of this strap. The LATCH connectors are the deluxe push-on style connectors. There are storage areas at the top of the shell to store the LATCH and top tether connectors when not in use. The tether strap can be used rear- or forward-facing. While tethering a forward-facing child restraint with a harness is always recommended, a top tether is not required for this seat. As I mentioned before, if a child is between 20-40 lbs. and is forward-facing, the SafeStop load limiter must be attached to the harness.


Note: Diono defers to the vehicle manufacturer for LATCH weight limits if your vehicle is older than MY 2005. If your vehicle requires you to discontinue the use of the lower anchors at 40/48 lbs. (or another weight limit), simply use the seatbelt for installation. Seatbelt installations are just as safe as LATCH, providing you can get a good, tight installation. Consult your vehicle owner’s manual for more specific information. Use of lower LATCH anchors in the center seating position with non-standard spacing is allowed only if your vehicle owner’s manual specifically allows it and the lower anchor bars are spaced 11″-14″ apart.

Crotch Strap Adjustment: There are three crotch strap positions located approximately 3.5”, 5.5”, and 7” from the back of the seat.

Adjustable Thigh Support: The sides on the Radian can be adjusted in or out depending on the size of your child. It adds up to 2.5” of width to the seating area when they’re adjusted out.

SafeStop Load Limiter: SafeStop load-limiting device must be used when installing with LATCH or when using the top tether, and the child weighs between 20-40 lbs.—so, since everyone knows to tether all the time, you essentially use the SafeStop when the child is between 20-40 lbs. I did have a problem getting my SafeStop attached to the splitter plate: the loop was sewn too tightly and couldn’t be finagled into place. At 4p on Friday, I called Diono to request a new one. Not only did they answer the phone at 4p, I didn’t have to explain myself silly trying to get the CSR to understand me. Awesome!

A Place for Everything And Everything In Its Place: Because one of the uses for the RXT is as a travel seat (it does fold, after all), there are storage spots for the tether, SafeStop, and lower LATCH connectors. These aren’t notches on the side of the shell, but actual storage cubbies. Neat-niks like me really appreciate cubbies. 😉

Padding, Comfort and Appearance: The name of the fashion I received is Storm: a dark gray with black accents. The well-padded cover is a comfortable textured velour with the only mesh being behind the child’s head and at the hips. I’ve been spoiled by other carseat covers that remove from the front without having to undo the harness, but the carseat cover and head wings cover were still easy to remove and put back on for washing. Diono recommends hand washing or a front loader washing machine. Other available covers are made of velour, ultrasuede, or nylon. Colors range from pretty jewel tones to more neutral tones.

Infant Support Cushions: Included with the RXT are separate head and body infant cushions. The head cushion has some padding behind the child’s head and caution should be taken to make sure the baby’s head doesn’t fall forward onto the chest with its use. The body cushion is nicely padded on the sides for positioning and there’s not much padding under the bum area.

Head Rest: AKA head wings by most people. The wings are comfortable and just the right distance apart so as not to induce claustrophobia. When a child is rf and using either of the bottom 2 harness slots, the head rest must be moved to the top-most position.

Cup Holders: So, how many cup holders does a carseat need anyway? Four! There are actually 3 slots on each side of the RXT that accept the cup holder, but due to the cup holder’s size, only 2 will fit next to each other on each side. One cup holder is included in the box with the RXT, so you’ll need to purchase extras if you want more.

8/10 Year Expiration: The RXT has 2 separate expiration dates. When used with the harness, the RXT expires 8 years from date of manufacture (not the date of purchase!). When used as a booster without the harness, the seat expires 10 years from date of manufacture. The manual specifies not to use the seat if it is in a crash.

Airplane Certification: The RXT is FAA-approved for use in aircraft. It also is a heavy restraint weighing in at 26.5 lbs., so if you do travel with it, you’ll want to use a luggage cart to avoid having to carry it. The RXT does come with a padded shoulder strap for carrying and I suggest buying another to be able to carry it backpack-style if you intend to carry it. Since the Radian seats are some of the narrowest on the market, you won’t have any problems fitting one in a plane seat AND the tray table will be able to come all the way down for a forward-facer. For rear-facing, the Angle Adjuster may make the seat fit depending on the pitch of the seats on the plane your flying. Buying a snack for the person in front of the carseat certainly doesn’t hurt ;). Remember that it can only be used with the harness on the plane since belt-positioning booster seats can’t be used on planes. Check out this action shot of the shoulder strap in use:


Value: Straps don’t twist and the deluxe SuperLATCH connectors are solid. The harnessed expiration date of 8 years is high in the land of convertibles, so this seat will be around your house for a long time. At a MSRP of $339, it’s expensive, but the RXT fills a niche nicely.

Construction: The Radian seats are made in China and are solidly constructed with steel supports. The cup holder arms also have some metal in them for security! Even though the carseat folds, it doesn’t feel flimsy.

Instruction Manual: Diono jumps on the technology bandwagon and uses QR codes you can scan with your smart phone to see videos of different sections in the manual. It works wonderfully! I had a question about how to route the seatbelt when the RXT is used in booster mode, so I scanned that section’s code and watched a video that answered my question. The pictures and drawings in the manual are also top-notch.



Weight: At 26.5 lbs. on my scale (Diono specs list it at 24 lbs.), the RXT is a heavy seat. This is where the steel support comes back to haunt you! Having the carry strap to carry the carseat around makes it much easier to transport it and it’s Bailey-approved! Every time the strap was on the floor, my dog went and laid on it, giving it her paw of approval.

Head Rest Doesn’t Stay in Place: I had issues with the head wings staying in the top-most position when my dd was sitting in the seat. I had to wiggle them up into position, but as soon as she adjusted the seatbelt or harness and leaned back, the head wings were uncomfortably resting on her shoulders. I wish they adjusted with wing nuts to tighten into place or some other way of clicking into position.

Use As A Booster: I wish, I wish, I wish the Radian could have been a true 3-in-1 carseat since it’s great at rear-facing and can hold big kids comfortably forward-facing too. Unfortunately, on the RXT model where the shoulder belt guides are integrated into the head wings, the seatbelt gets caught in between the cover and the belt guide. Belt fit is very good and has a good geometry, but when my dd leaned forward, slack remained in the seatbelt when she leaned back, reminiscent of the boosters from years ago that had the same problem. This happened in all 3 middle row seating positions in my MDX and in my dh’s Lexus RX330. Since we know kids move in their boosters and don’t always pull the seatbelt tight, it’s a big concern if the seatbelt doesn’t retract to be snug all the time. I would either lock the retractor so the child can’t lean forward or use it as a booster in emergencies only.





OK. Anyone who knows me knows how much installation trouble the previous generation of Radian gave me in my Sienna. But that’s water under the bridge now that I have an Acura MDX. Just like any other carseat, there will be times when a Radian fits a vehicle well or is a challenge. The SuperLATCH connectors are differently shaped than their cousins, the “regular” push-on LATCH connectors, so it can be more difficult to push them through stiff upholstery to attach to the lower anchors. I should note at this point that there are clips on the side of the seat that secures the strap that keeps the LATCH connectors attached to the carseat. A couple of times, in my hurry, I forgot to pull that strap out of the clips and it *does* make a significant difference in installation tightness.

Rear-facing: I didn’t have any problems installing the Radian rf  in either of my vehicles using either LATCH or the vehicle seatbelt. The angle was good, not overly reclined, and installation was tight. The Radian installs at one angle rf: the carseat must be installed with the recline foot attached and no noodles are allowed. Some older rf kids find this to be too reclined and Diono has a solution. The Angle Adjuster “wedge” sits just behind the recline foot and boosts the back of the Radian up so the child is sitting more upright. Because it does alter the angle more upright, Diono specifies that your child should have good head control (like an 8 month old would). A benefit of a more upright angle is two-fold: the bigger child is less likely to ramp up the carseat in a frontal crash and parents will be able to move the front seat back so their knees aren’t jammed into the dashboard. The Angle Adjuster does save some serious space—several inches worth—so if your Radian has you jammed up in the front seat, it’s money well-spent.


Forward-facing: Here’s where I was nervous about the fit in the vehicle. The ff belt path on the Radian is pretty low, in part because there’s no base. In the past I’ve found the seatbelt latchplate tends to hit the edge of the ff belt path and that can cause problems with getting the seatbelt tight. If you can’t twist the buckle down to move the latchplate down a bit, a tight installation may elude you. I was able to twist my buckle stalks in my MDX and reposition the latchplate, which made installation a breeze. It’s not pretty to look at, but it’s very tight. Some folks find that reclining the base changes the angle of the belt path just enough for a successful install. I didn’t have to do that in either the MDX or the RX330. The open belt path behind the cover means that you have easy access to either the seatbelt or the LATCH strap to pull tight.





  • Weight Limits: The Radians currently have a higher than average rear-facing weight limit, so it will accommodate those extended rear-facers or very large children to a safe age for ff. The high ff weight limit means a wider range of kids will fit the seat for a long time.
  • 5 Harness Slot Positions: Allows for a more closely fitting harness on the child. High top harness slots mean the seat can be used harnessed for the tallest child.
  • 3 Crotch Strap Positions: Having a choice of crotch strap positions makes the harness more comfortable for bigger kids.
  • Low and narrow footprint means it’s more likely to fit in tight spots.
  • Padded Cover: A thickly padded cover, plus the memory foam in the bum area, makes for a comfy seat.
  • Instruction Manual: Don’t understand what you’re reading? Scan the code and watch a video! How cool is that?!


  • Low LATCH weight limits
  • Harness Adjuster: It’s tug-tug-tug can be frustrating for some used to a smooth adjuster on an infant seat.
  • Installation: Often more difficult depending on the vehicle, with a higher learning curve due to the various features.
  • Sliding head rest: Having to adjust the head rest up every time my dd sat in the seat was a pain.
  • Snug fit of the shoulder belt in booster mode is poor; shoulder belt can get caught leaving slack.
  • Relatively expensive and heavy

Recommended-150pxThe Diono Radian RXT is a solid convertible seat with great rear-facing features. Its high height and weight limits accommodate big kids both rear- and forward-facing, yet it takes up less space than many of its competitors. For narrow backseats or 3-across situations, you simply can’t beat the width of the RXT. Features like rear-facing tethering, thick padding, and solid construction make the Radian RXT a solid purchase.


Webpage for the Diono RXT http://us.diono.com/en/car-seats/radian-rxt


Thank you to Diono for supplying the RXT used in this review!

Updated: May 16, 2016