1. Home
  2. Baby Gear

Diono Radian vs Rainier – Which Car Seat is Best?

We’re supported by moms. When you buy through links on our site, As an Amazon Associate, I may earn a commission.

When you think of car seats Diono is not the brand that first pops into your mind. But this brand is known for making car seats that are high-quality and designed for children of all ages and sizes. 

We have looked at two of their convertible seats the Diono Radian 3XRT and the Diono Rainier 2AXT.

Now at first glance, these car seats would appear almost identical except for their name but there are a few key differences between them that may impact your decision as to which one you purchase.

Both car seats are designed to be a slimmer fit than most conventional car seats. This would allow you to fit three Radian car seats in the rear seats of most vehicles but with the Rainier, this would not be possible. 

They both come with the infant insert pillows and memory foam infant body support cushion. This makes the car seats as comfortable as possible for your children from the very first time that they use their seat.

Both seats are equipped with the Diono SuperLATCH system that ensures seats are correctly fitted in the vehicle each and every time by having an audible click that lets you know it is correctly fitted.

Prices pulled from the Amazon Product Advertising API on:

Main Differences Between Diono Radian 3XRT vs Rainier 2AXT

Here are the main differences between the Diono Radian and Rainier:

  • The Radian has a slim fit enabling you to fit 3 car seats across in most vehicles, while the Rainier is slightly wider.
  • The Radian is available in eight color options while the Rainier is only available in seven color
  • Although both have aluminum reinforced side walls only the Rainier has the extra deep side walls providing an extra layer of protection in the event of a side impact.

Diono Radian 3XRT

Diono Radian 3RXT, 4-in-1 Convertible Extended Rear and Forward Facing Convertible Car Seat, Steel Core, 10 Years 1 Car Seat, Ultimate Safety and Protection, Slim Design - Fits 3 Across, Purple Plum

At the very first glance of the Radian 3XRT, you can see that it has a slim body allowing for those three across the rear seats.

You may be thinking that this is a car seat that is designed for older toddlers and children, but in fact, this car seat will begin its journey as a rear-facing seat suitable for newborn babies from five pounds.

It can be used in this rear-facing position until your baby is 50 pounds, allowing you to keep them rear-facing for as long as possible.

Once they reach the 50-pound rear-facing weight limit the seat can be turned to forward-facing and can now continue to be used until your child reaches the maximum weight limit of 120 pounds.

This car seat is potentially the only car seat you will ever need to purchase for your child making it one of the best value for money car seat options.

The Diono Radian 3XRT is designed to fit your child right from birth all the way up until they no longer need a car seat at all, not just until they need a booster seat but absolutely no car seat at all! This car seat is a complete win-win product.

And just because this car seat can be used until the maximum weight limit of 120 pounds is reached do not think that they have compromised on safety – they haven’t!

This car seat is made with a dual spine and a high strength steel frame designed to withstand a significant force. It also has side impact protection that comes with aluminum reinforced sides for that added peace of mind.

An added bonus of this car seat is that it can be used for traveling and so is foldable. It is also fully approved for use in an aircraft.

There is no doubt that this car seat will have your little one covered for many years to come!

diono radian

Car Seat Features


It has an engineered reinforced steel core that is made from automotive-grade high strength steel. It also uses the SuperLATCH connectors for super secure and easy installation every time.


The Radian comes with a 12 position adjustable headrest that can protect your child up to a height of 57 inches. 

Child Weight Range

This seat is designed for children from 5 to 120 pounds, approximately from birth to ten years old.


The Diono Radian 3XRT is currently $329 on Amazon.com. But you should definitely check out the Diono website for any special offers.


  • You can fit three seats across the back seat of most cars.
  • It is affordable in that it is probably the only car seat you will need to purchase – a maximum weight of 120 pounds.
  • Quite easy to install and move to other vehicles using the SuperLATCH system.
  • The seat folds flat making it perfect for traveling and can be used in airplanes.
  • Fully convertible seat
  • Steel frame.


  • Although designed for traveling the seat is quite heavy.
  • Harnesses can be difficult to adjust along with the seat belt adjustment.
  • No cup holder built into the seat.
Buy on Amazon


Diono Rainier 2AXT

Diono Rainier 2AXT All-in-One Convertible Car Seat, Grey Dark

The Diono Rainier 2AXT at first glance looks almost identical to the Radian except that it is slightly wider meaning that you would not be able to fit three of these car seats in the rear seats of most vehicles.

It does include all the same safety and comfort features with a few extras. The Rainier has deeper sidewalls for not only added comfort but extra protection for your little one.

The Rainier is suitable from newborn to approximately 10 years old, 5-120 pounds in weight. This car seat can remain rear-facing for an extended period of time with a maximum weight limit of 50 pounds.

It can then be turned into a forward-facing car seat with a weight limit of up to 120 pounds. This should see you through your child’s car seat journey without the need to purchase any additional seats.

It is made from high strength steel with a dual spine that redirects the energy from an impact away from your child and so helps to keep them safe in the event of an accident.

The seat also has energy-absorbing foam added for side impact protection as well as the extra-deep sidewalls. Whatever age or stage your little one is at this car seat is designed to hug them in all the right places while keeping them safe and comfortable. 

The Rainier is also a great option if you intend to travel with your little one as it folds completely flat and is approved for use in airplanes. Although it may be a little heavy to carry around.

diono rainier2

Car Seat Features


It has an engineered reinforced steel core that is made from automotive-grade high strength steel.

It also uses the SuperLATCH connectors for super secure and easy installation every time, as it comes with an audible sound that lets you know that it is fitted correctly.


The Rainier comes with a 12 position adjustable headrest that can protect your child up to a height of 57 inches. 

Child Weight Range

This seat is designed for newborns to approximately 10 years old, with a weight limit of 5-120 pounds.

The Rainier can be used rear-facing from 5-50 pounds, forward-facing with integrated seat belts from 22-65 pounds, and then in booster seat mode from 50-120 pounds.


The Diono Rainier 2AXT is priced slightly higher than the Radian, it is currently available at $303 on Amazon.com. But it is usually priced at a higher price than the Radian. 


  • The Rainier allows you to keep your little one rear-facing longer with a weight limit of 50 pounds.
  • It has built-in memory foam and an infant car seat insert for your newborn. 
  • It comes with deeper sidewalls for extra safety.
  • It has a steel frame.


  • You can’t fit three of these car seats across the rear seats of most vehicles.
  • The Rainier is a little pricier than the Radian.
  • Very difficult to position the seat correctly rear-facing.
  • Straps are difficult to tighten due to being sealed.
Buy on Amazon


Diono Radian vs Rainier – The Winner Is…

Both of these car seats are solid options with no major differences between them, making the decision of which to purchase even more difficult.

One of the deciding factors for many parents may be the fact that the Radian allows you to fit three seats in the rear seats of most vehicles. The Radian is normally a little cheaper than the Rainier which may also make it the overall winner for many parents.

Both the Radian and the Rainier are solid options that have a long life and will last until your child is around 120 pounds. This means that either of these car seats should be the only car seat you will ever need to purchase for each of your children.

Although the initial cost is a little on the expensive side as it should last around 10 years it makes these seats very good value for money.

The Final Thought

Choosing a car seat requires some real deep research on the part of most parents and deciding to go with a less known brand can be a risky decision.

But both the Radian and Rainier have proved to be solid options and good value for money if you are looking for a convertible car seat.

Hi, I'm Emma and I'm a mother to 5 beautiful children aged from 1 to 21 years old- life is hectic! I have learned so much along the way, not only from my own children but also through my professional life. In my positions as a Childminder and Teaching Assistant, I have studied Child Development and The Early Years Developing Practice. I wish to share all of this knowledge and help you with your own parenting journey!