Diono Rainier Review: Diono Adds Depth to Its Convertible Lineup

Updated 11-08-18

Rainier Houndstooth

2018 Diono Rainier Review

Recall notice: most Diono convertibles, including the Radian RXT, were recalled in October 2017. See recall details here.

Around thirteen years ago, a folding carseat with steel metal structure hit the market and made quite an impact on the way children started riding in cars. The Radian was a tall, skinny seat with a low profile that made it ideal for narrow seating positions and tight 3-across scenarios. Then in 2009, a headrest was added for more side impact protection. A branding change in 2011 allowed Diono to update the Radian line to include belt guides so the carseats could further their usefulness as belt-positioning booster seats. In 2014, Diono introduced the Rainier, Pacifica, and Olympia line of carseats. In Summer 2018, Diono discontinued the Olympia and Pacifica models and freshened the Rainier. The new Rainier 2 AX and 2 AXT replace the Pacifica and Rainier lines. This review will cover the Rainier model made prior to the 2 AX changes that were introduced in September 2018.

Rear-Facing Weight Limits Forward-Facing Weight Limits Booster Weight Limits Features


Olympia Graphite*Discontinued

5-45 lbs. 20-70 lbs. 50-110 lbs.
  • shoulder belt guide for booster use is attached to fabric cover


Pacifica Sunburst


5-50 lbs. 20-90 lbs. 50-120 lbs.
  • added structural support for weight limits
  • infant support pillows
  • memory foam under bum
  • shoulder belt guide for booster use is attached to fabric cover


Rainier Orchid

5-50 lbs. 20-65 lbs.; seats made prior to 9/17 are 20-90 lbs.  50-120 lbs.
  • added structural support for weight limits
  • infant support pillows
  • memory foam under bum
  • adjustable headrest
  • shoulder belt guide for booster use is attached to headrest
© www.CarseatBlog.com

Rainier Basics

  • 5-50 lbs. rear-facing with at least 1.5” of carseat above the child’s head or total height of 44”
  • 20-65 lbs. forward-facing with a child less than 57” tall
  • 50-120 lbs. as a booster with a child less than 57” tall and child’s shoulders must be at or above the 4th set of harness slots


  • Full steel frame and aluminum reinforced sides
  • SuperLATCH™ connectors with Secureweave™ webbing
  • Aluminum reinforced 12 position adjustable headrest
  • Folds flat for travel or storage
  • Can be tethered rear-facing
  • Energy absorbing EPS foam in headrest and torso area
  • Infant body support cushions and memory foam for added comfort

Rainier without cover head low Rainier without cover head high Rainier without cover head offset Rainier without cover side


  • 5 harness slot positions: 8”, 9.5”, 11 ½”, 14 ¼”, 17”
  • 3 crotch strap positions: 4”, 6”, 7 ¼”
  • Outside width: 18” at shoulders, 16” at red lap belt guides
  • Interior width: 14” at shoulders, 12.5” at hips
  • Seat depth: approx. 12”
  • Seat weight: 26 lbs. without detachable rear-facing foot, 27.2 lbs. with foot

Diono Rainier colors

SafeStop Load Limiter

The SafeStop load-limiting device is a small strap attached to the upper back left of the seat and is designed to increase the amount of time a small forward-facing child experiences crash forces. This ride down time allows energy to dissipate. The SafeStop must be used when installing the Rainier forward-facing and the child weighs between 20-40 lbs.

Rainier Safe Stop stored  Rainier Safe Stop in use

Rainier vs. Radian RXT

The $64,000 question is: how does the Rainier stack up next to the Radian RXT? If you look at the bottoms of the seats, they look the same. The harness slots measure the same and the width inside at the shoulders is about the same. The differences start with the upper shell, where the Rainier slopes outward and forward as it gets taller, providing more torso and head protection. The Rainier is wider at the top by about an inch. That’s it, but it can make a difference if you have a tight 3-across in your small back seat.

Distance btwn ff Radian rf Rainier FF Rainier Radian Radian Rainier front Radian Rainier side Rainier Radian top down

Installation/Fit to Vehicle

Installation of the Rainier is going to be very specific to your vehicle, just like the Radian is. Because the Rainier is based on the design of the Radian, the way it fits vehicles can sometimes be finicky. That’s OK if you know the tricks of installing your Rainier. But don’t let me scare you off either! I’ve installed my Rainier with very little effort in some vehicles.

The recline foot for rear-facing, called the “detachable base” in the manual, has toes that are designed to stick into the seat bight (crack) of the back seat. If your vehicle seat has plastic covering the hinges where it folds forward—like SUVs and sometimes vans have—the toes won’t be able to “dig into the sand” and create a tight fit to your vehicle. This recline foot also makes it so that the Rainier has but one recline angle since Diono doesn’t allow the use of pool noodles to adjust for angle: you get what you get and you don’t throw a fit. The recline angle is very much a marriage of the angle of your back seat and that recline foot.

Rainier rf recline foot Rainier rf in bight

However, Diono does make an Angle Adjuster accessory (sold separately) that allows for a much more upright installation for older children who have good head control.

Diono Rainier Angle Adjuster Diono Angle Adjuster

Below are pictures of the Rainier installed rear-facing with and without the optional Angle Adjuster accessory.

Diono Rainier installed without AA  Diono Rainier with Angle Adjuster installed in Freestar

For more info on rear-facing space issues and to see how the Rainier compares to other convertibles in this regard, see our Rear-Facing Convertible Space Comparison.

One bonus feature of the Rainier is that it can be tethered when rear-facing to reduce rebound movement after a crash. Rather than go into the how’s and why’s of rear-facing tethering, I’ll simply link to a more in-depth blog I wrote on the subject: How to Use A Rear-Facing Tether. Diono allows Swedish-style tethering for the Rainier and all their other convertibles.

RF Rainier tether in Acura MDX RF Rainier FF Radian with dolls

The narrow, closed rear-facing belt path can make it difficult for some folks to get the seat belt or LATCH belt threaded through. You may find yourself using your tippy fingertips to grab the seat belt latchplate to pull it through to buckle it in. A long buckle stalk can also interfere with pulling the seat belt tight since there’s no good way to grab the seat belt to pull slack from it.

Rainier rf belt path

On the flip side, the forward-facing belt path is open and easy to access. A plastic panel sewn into the cover protects the child’s back from feeling the seat or LATCH belt. The Rainier, like the Radian, will tend to slip forward on a vehicle seat when installed forward-facing due to its design. If you find this happens after installation, dropping the adjustable bottom of the seat down and reinstalling usually solves this problem.

Lower LATCH anchor weight limits:
Rear-facing: 35 lbs.
Forward-facing: 40 lbs.
Once these maximum weight limits have been met, switch to using the vehicle seat belt for installation.

Center LATCH installations with Non-Standard Spacing:
Center LATCH installations with non-standard spacing are allowed as long as the spacing is between 11-14″ and the vehicle manufacturer allows it as well

Inflatable Seat Belts
Diono has determined that the Rainier CAN be installed with inflatable seat belts found in some Ford and Lincoln vehicles. This does not include inflatable belts found in other vehicles or airplanes. Check your vehicle owner’s manual and the tags on the seat belts to see if you have this type of seat belt. These seat belts can also be identified by their thickness: they are much thicker than their non-inflatable counterparts to accommodate the airbag.

This seat does NOT have a built-in lockoff device for installations with seat belt so it’s very important to understand how your seat belt locks if you’re going to install with seat belt and not with LATCH connectors. Remember, once your child reaches 35 lbs. rear-facing, or 40 lbs. forward-facing you must discontinue using the lower LATCH connectors and switch to a seat belt installation instead. All vehicles made after 1996 have seat belts that can lock in some way to hold a carseat tightly in place during routine driving. Most vehicles have switchable retractors but some vehicles or specific seating positions have locking latchplates instead. It’s important to know what your vehicle has and to understand how these features work before you install this carseat with a seat belt. See your vehicle’s owners manual for specific information on how to install a carseat in your vehicle using the seat belt. If you have questions, please visit our car-seat.org forum and we’ll be happy to help answer them.

Fit to Child

My newborn-ish size doll, Romeo, who is about the size of a 9 lb. newborn, fit in the Rainier with the infant inserts added. For Romeo, I did remove the harness pads because of their length. When I tried an actual 9 lb. 6 week old in the seat, he just made it to the bottom harness slots with the infant inserts added. Use with a smaller baby should be evaluated on a case-by-case basis since the harness should always come from at or below the baby’s shoulders and the harness straps should be snug. The slots were above both the doll’s and baby’s shoulders when the padding was removed.

Rainier Romeo Rainier Sam  

Older rear-facing kids fit great in the Rainier, as you can see from the pic of the 4 yr old below. The angle adjuster makes it a more “mature” angle for her and she has plenty of legroom. She’s happy to fold her legs or leave them as they are, and the headrest provides a nice place to rest her head for sleeping.



The Rainier works well for forward-facing kiddos too. But with 17″ top harness slots, a 57″ height limit is unrealistic.

Diono Rainier - stock FF

Using the Rainier as a belt-positioning booster is problematic. Fit of the belt on a child is actually quite nice and I anticipate the Rainier will receive an IIHS.org rating of Best Bet, just like the Radian RXT did. So what’s the problem then, you ask? The shoulder belt positioner is tucked far back in between the headrest and the side of the carseat. The padding and fabric from the cover create friction on the seat belt and grab it when the child leans forward and keeps the belt away from his body—that’s dangerous in a crash.

Rainier shoulder belt guide

If a child doesn’t move and the seat belt stays tight, there’s no problem. But most children will move at some point during a journey longer than a few minutes. Watch the video and you’ll see.

Since there are still some Rainier seats out there with the 90 lbs. weight limit, this section on harness pads will be useful. If you have a newer seat with a max weight limit of 65 lbs., your carseat only has the shorter, thicker set of harness pads that you will use when forward-facing (optional for rear-facing). The manual says that 2 sets of harness pads are included: one set for children under 65 lbs. and one set for children over 65 lbs. I called to verify their use because the wording in the manual is vague and the shorter set is very long for infants. I was told they could be removed for rear-facing but they are mandatory for forward-facing mode. The under-65 lb. harness pads have a grippy material inside to grab the harness in the event of a crash and are padded with memory foam. The other set of harness pads, to be used with children over 65 lbs., are attached to a length of harness webbing with a metal plate on the end that is threaded through the same harness slot being used by the child. The shiny grippy material is on the backside of these pads and will rest against the child’s torso. *A note about these over-65 lb. harness pads: the instructions for their use are on a tag sewn inside one of the pads. Open the Velcro on one of the pads to see the instructions.

Rainier harness pads comparison Rainier long harness pad instr Rainier over 65 lbs harness pads


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. The harness must be unthreaded through the harness slots, but the lap straps are not threaded through the cover. Diono recommends hand washing or a front loader washing machine. Cover choices vary by retailer, but specialty stores will be carrying a striking black and white houndstooth. For daily clean-up, just stay on top of the crumbs to keep them out of the crevices inside of the seat.

Ease of Use

I think it’s important to note how the harness adjuster works on the Rainier. I’ve seen a lot of comments on the RXT (its sister seat) where users have been frustrated at being able to get a snug fit with the harness—that it’s been hard to pull. What I’ve found is that the harness adjuster is an initial long pull followed by several short tugs. If you leave the harness relatively tight to begin with as your child gets out of the seat, you’ll most likely be using the tug-tug-tug method to tighten the harness.

FAA-Approval/Lifespan/Crash Guidelines

Diono convertible seats were originally designed as travel seats, hence the ability to be folded (nevermind the weight). Like 99% of all harnessed carseats, the Rainier is FAA-approved for use on an airplane. If you do decide to fly with it, you’ll probably want to purchase a carry strap or two so you can carry it slung over one shoulder or worn backpack-style. If you use it rear-facing on the plane, keep in mind that it will most definitely rest against the seat in front of it. An angle adjuster will definitely help with more space, but the person in front still might not be able to recline their seat.

If you have a Rainier made after September 2017, your carseat has a 10 year lifespan. If your Rainier was made before September 2017, it has an 8 year lifespan when used as a harnessed seat, which is a nice length of time. If you decide to also use it as a booster, that lifespan lengthens to 12 years. If you have any questions, give Diono a call at 1-855-463-4666.

Replace the Rainier after a crash. Diono follows the one-time-only guideline for crashed restraints: if it’s in a crash, don’t use it again.

Rainier Advantages

  • High maximum rear-facing weight limit: 50 lbs!
  • Narrow for tight 3-across installations: while not as narrow as the Radian RXT, the Rainier is still a pretty narrow carseat
  • EPS foam in all the right places
  • Tether that can be used rear-facing
  • 12 position headrest for side impact protection and support
  • 3 crotch strap positions
  • Low sides means easy loading/unloading of child
  • Expandable sides for leg comfort
  • Folds flat for travel or storage


(In all fairness, these aren’t necessarily problems but I list them here to inform potential consumers of specific Rainier issues)

  • Heavy seat: the Rainier weighs 26 lbs.
  • Narrow, closed rear-facing belt path
  • Difficult to move crotch strap positions
  • No built-in lockoff for seatbelt installations
  • Takes up a lot of front-to-back space when installed rear-facing without the angle adjuster
  • When used as a belt-positioning booster, the shoulder belt gets caught in the belt guide and leaves slack—we don’t recommend it as a booster for this reason
  • Finicky install in some vehicles
  • Made in China


Diono Rainier The Diono Rainier is a nice addition to Diono’s carseat line. The high rear-facing weight limit and tall shell will get even the largest child to at least age 3 rear-facing and smaller kiddos have made it to age 5 and beyond. The more robust side wings provide that extra protection parents are looking for as they compare carseats for their children. Diono sacrificed a mere inch for the extra structure, but kept all the other great features, like a rear-facing tether, expandable sides, and comfortable padding to create a well-rounded harnessed carseat.

Of course, the best advice for any carseat is to “try before you buy”.  If try before you buy isn’t an option, make sure you research the store’s online return policy – just in case it doesn’t work out for some reason. Free shipping and hassle-free returns is one of the many reasons we love Amazon for carseat and baby gear purchases. 

For more information on the Rainier, head to the official webpage: http://us.diono.com

Thank you to Diono for providing us with this Rainier for our review!



  1. Katie November 11, 2017
    • Kecia November 12, 2017
  2. Efrat May 15, 2017
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    • Heather May 17, 2017
  3. Erin Moeller May 11, 2017
    • Heather May 12, 2017
  4. barb January 20, 2017
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  5. Jessica Tucker January 3, 2017
  6. Melissa December 1, 2015