Diono Radian vs Rainier Car Seats

Diono Radian vs Rainier – Which Model Is Best?

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When choosing a car seat for your child it will likely be an exercise in you balancing how comfortable it is when they are sitting in it and wanting the safest seat possible for them.

One of the top child car seat manufacturers, whose child seats offer safety and comfort in abundance, is Diono. They have an outstanding reputation for high-quality car seats and offer a wide range of child seat products and accessories.

In this review we are going to assess the merits of two of their most popular child car seat ranges – the Diono Radian and the Diono Rainier. These two product names sound very similar, but as you will soon see there are several differences between them.

Why Choose a Diono Car Seat?

Diono Radian RXT Car Seat Award
Diono Radian RXT Car Seat Award
Diono Rainier Car Seat Award

Diono originated in the innovative city of Seattle in 1999. Their car seats were an immediate success, winning awards for their innovative design and safety features. Diono soon established itself overseas and now operates in 54 countries across the globe. They have offices in the United States, United Kingdom, Canada, France, Germany, Hong Kong and China. 

In 2015 Diono made their seventh appearance on the Inc. Magazine’s 500 Fastest Growing Private Companies”. They are also on Inc.’s list of “Top Consumer Products & Services”.

Diono's Radian Convertible Car Seat was first released in 2005 and was the first steel-reinforced folding car seat. The Radian was also recognized with several honors:

  • Pregnancy & Newborn “Reader’s Choice Award"
  • Star
    Creative Child “Top Choice of the Year”
  • Star
    Parent Tested Parent Approved “Seal of Approval”
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    National Parenting Center “Seal of Approval”

We are fans of the Radian RXT in particular here at Kid Sitting Safe and have featured it previously in our All-in-One Car Seat Reviews. We also found it is one of the smallest convertible car seats, which is often an essential need for those parents looking to fit 3 seats across the back. In fact, this is one of the unique selling points for all Diono car seats.

Diono are passionate about engineering products that are all about safety and smiles. As well as car seats, their product range includes strollers and carriers.

Diono Radian Versions


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The Diono Radian is available in three different versions, namely the new Radian 3R and 3RX models (replacing the older R100 and R120 models respectively) and the Radian RXT. Despite having similar names there are several features which differ within each one.

Some of these variations are slight and may not make much difference to your buying decision, while others may be more significant to you.

Diono Radian vs. Rainer Comparison

Weight Limits

First, we need to look at one of the most important differences, and that is the weight limits which each of them can hold. Other features of these Diono child car seats are of no consequence if the seat's weight limit is not compatible with the weight of your child.

Radian 3RX & RXT             

Radian 3R                     


Rear Facing              

5 lbs. - 45 lbs.                  

5 lbs. - 40 lbs.               

5 lbs. - 50 lbs.

Forward Facing        

20 lbs. - 80 lbs.              

20 lbs. - 65 lbs.            

20 lbs. - 65 lbs.


50 lbs. - 120 lbs.   

50 - 100 lbs.                 

50 lbs. - 120 lbs.

As you can see, the Radian 3R has a slightly lower weight limit when the seat is rear facing, but on forward facing it is a full 15 lbs. lower, which is a significant difference in the context of a child's weight.

The top car seat for rear-facing use is the Rainer which goes up to 50 lbs. When your child is big enough to move to a booster, again the 3R is a bit behind of the others.

Construction and Safety

Diono Radian RXT All-in-One Convertible Car Seat, For Children from Birth to 120 Pounds, Shadow (Discontinued by Manufacture)

​All Diono car seats have frames made with solid steel to provide them with strength and stability. More reassuring are the reinforced aluminum sidewalls that offer your child added protection, should your car be hit side-on.

These are designed to absorb the energy of an impact, and this is enhanced by EPS foam, which is a significant component in the construction of the car seat's side walls.

The Rainer's side walls have this protection; however, its side walls are slightly thicker; therefore, they offer that little bit more protection than the others.

Harnesses, Straps and Buckles

All four Diono child car seats have a harness configuration which has 5 straps and 3 different buckle positions. This allows them to be adjusted and secured so that your child is both secure and comfortable.

The harness is Diono's trademarked 'Safe Stop' version which is designed to absorb energy safely should your car be in a collision, and the child seat is in the forward-facing position.


Both the Diono Radian 3RX and the Radian RXT have memory foam in the seat cushion for added comfort, which the 3R does not have.  As you'd expect, the Rainier also has a memory foam cushioned seat.

Where the Radian RXT and the Rainer have an advantage over both of the Radian 3R and 3RX models, is in the head area. They have fully adjustable headrests which help to keep children of all ages comfortable.

In addition to this, they both have side headrests. These are particularly welcomed by older children who can rest their head against it when they want to sleep on long journeys.

The Rainier just edges it over the RXT for comfort due to it being slightly wider (18 inches vs. 17 inches)

For those parents with infants, you should be aware that other than the 3R, all these Diono car seats come with an infant support pillow to provide the support an infant’s head needs because their neck muscles are not yet strong enough.

Ease of Installation

There's no difference here as all Diono car seats use their in-house and trademarked 'SuperLATCH' system. This has both a visual indicator and an audible click when the seat connectors are locked in place correctly. The base of the all their seats has rubber grips to prevent it sliding as you install it, or when placing your child in it.

Color Options

While it may not have as much importance in comparison to safety and comfort, it is always nice when you have a color choice so that you can match your child's seat to the rest of your car's interior.

Thankfully, all versions of the Radian have at least 8 colors available, with the RXT having the most, with no fewer than 14 color options. The Rainier isn't quite as kaleidoscopic as the Radian, with only 5 different color options

Other Features

The rXT and the Rainier have cup holders which neither the 3R nor 3RX have. All the child seats can be folded flat when not in use, and they are also all FAA certified, which allows them to be used on aircraft.


Radian 3R
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Radian 3RX
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Radian RXT
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Diono Rainier 2AX Convertible Car Seat, Black

While prices can fall and rise slightly, in most cases you will find that Radian 3R is the cheapest of these four seats, which is not all that surprising with the others having a greater weight capacity.

Next, you have the 3RX, whose price is competitive given that it has the same weight limits as the RXT, albeit not all its features. The Radian RXT is normally priced higher than the other two Radian models.

The Rainer has the highest price, and this is not surprising as it has enhanced features in comparison to the others. It also has the greatest weight capacity, and thus the longest expected usage in terms of your child's size and age as they grow older.


To do a fair comparison between the Diono Radian range of child car seats and the Diono Rainier, we really need to compare the Radian RXT with the Rainier, as they are the closest in terms of features.

However, we must point out that the 3RX is a worthwhile option, especially as its weight limits are the same as the RXT.

The Radian 3R shouldn't be dismissed, not least because its safety features compare favorably, and in many aspects are identical, to the others. If you are on a budget, a lower price makes it worth considering.

The Diono Radian RXT vs. Rainier comparison is a tight race, with both have very high specifications. However, for the little bit extra you will pay, the Rainier has the following advantages over the others:

  • Greater weight limits so it has longer use as your child grows
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    Wider top area for greater comfort
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    Thicker side walls for enhanced side impact protection

There may not be many differences, but they are features which relate to your child's comfort and safety, and these surely must be the ones which most influence your choice.


Robert is a father of a young daughter and has developed an expertise in child car seat safety. He is a keen supporter of the use of child safety systems having seen his daughter come away from a side impact collision unscathed due to the use of a child car seat. When he's not spending time reviewing child safety systems he works as a Technical Manager on major construction projects.

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