What Will Work with My Toyota Sienna Hybrid Front Wheel Drive to Help the Squat in the Rear?

Updated 04/21/2026 | Published 04/06/2026

Products Featured in This Question

Firestone Coil-Rite Air Helper Springs - Rear Axle

(761)

$158.89

Timbren Suspension Enhancement System - Coil Spring Suspension - Rear Axle

(7039)

$207.69

Question:

Hi, I’d like to ask an expert about 2024 Sienna hybrid fwd. trying to fix rear end sag. Firestone 4155 sounds like it might not work with hybrid, is that right? Any other suggestions for products to fix the sag? Thanks!

asked by: William N

Expert Reply:

Hello William,

Thanks for writing in, you are correct the Firestone #F4155 is not a good fit for the 2021 to 2024 Sienna Hybrid. The hybrid models have some key differences in the rear suspension area due to battery placement and tighter coil spring spacing. Because of that, air bag kits like the 4155 do not have confirmed fitment, which can lead to interference or installation issues and the possibility of still dealing with rear sag after spending the money.

A much better and proven solution for your Sienna Hybrid is the Timbren Suspension Enhancement System, # T58GR. This system installs inside the rear coil springs, so it avoids the clearance concerns that come up with air bags on the hybrid. It uses a progressive rubber spring design, meaning it only engages when weight is added. That allows the ride to stay comfortable when unloaded while still giving you the support you need when carrying gear.

This is a really solid way to get the confidence you are after. Instead of worrying about whether something will fit or hold up, the Timbren kit gives you consistent support right where you need it. When you load up the rear, it helps keep the van level, improves stability, and reduces that sagging or bottoming-out feeling, so you are not dealing with scraping or a loose, unsettled ride.

Another big plus is how straightforward it is to install and live with. There are no air lines, no pressure adjustments, and no maintenance. It is a simple bolt-in upgrade, and once it is in place, it is always working in the background to support the load. If you want, I can also help you confirm fitment for your exact model year and walk through what the install looks like.

I definitely understand not wanting to risk spending money on something that may not fit or solve the problem. The Timbren kit removes that guesswork and gives you a dependable way to keep your Sienna sitting level and feeling stable when it matters most.

What do you usually carry when the rear sags, bikes, tools, camping gear, or something else?

expert reply by: Kate F

Timbren Coil Spring Enhancement Installed
(click to enlarge)

Bill J.

4/14/2026

I have these very same bags on my 2022 Toyota Sienna XLE Awd. You do need to use a lift to be able to install. I used a professional installer for mine as it is complicated to install. See this link to see why> https://www.etrailer.com/Vehicle-Suspension/Firestone/F4155.html Best regards, bill ps Mine are still working great and I enjoy them very much. I like a stiff ride so I keep 10 lbs in them all the time.

Kate F.

4/15/2026

@BillJ Thanks for the response Bill, I love that we started having neighbors (customers) comment on our answer pages. It is so nice to hear that first hand experience =) A little soapy water goes a long way to get those air bags into the coils.

Tom S.

4/14/2026

I had mine professionally installed. We can’t get them to hold air more than a day. I might switch to Sumo springs.

Kate F.

4/15/2026

@TomS Have you checked the fittings? Fill them up and spray some soapy water on them to see where the air is coming out. Also, when you do not need them, how much air are you keeping in them?

William N.

4/15/2026

Thanks Kate. I've read about these Sumo Springs and similar foam enhancements for the shocks and they have mixed reviews. The real car nerds seem to think they are no comparison to an air bag system or even a leaf spring helper. Do you have personal experience with this product? All my best and thanks again for the thoughtful response. We are mostly carrying around bikes and camping gear and lots of kids in the car. :) Will

Kate F.

4/15/2026

@WilliamN The people are right, Air Bags are better over the other options. Mainly because you can fine tune them to your set-up by adding or taking away air. I really wish I knew of an option for the Hybrid model for you. I double checked with Firestone, and they confirmed that they will not work on the Hybrid model. I have personally not used the Timbren Coil Springs, I have heard that they do help as they do help stiffen up the coils, and something is always better than nothing.

Bill

4/21/2026

@KateF This kit does require having your Sienna *4th Gen on a rack as it can not be done very easy on the ground. I used a professional installer to do my on my 2022 Toyota Sienna. Here is a link that will help you to understand. https://www.etrailer.com/Vehicle-Suspension/Firestone/F4155.html I love mine and they are still working well after some time and miles. Hope this help. I love the way they work.

Kate F.

4/21/2026

@Bill Thanks for the response, Bill. I wasn’t aware the Sienna needed to be on a lift, that’s a great callout for anyone planning the install. It may not require a full lift, but you’ll definitely need to get it up off the ground some. I can squeeze into some pretty tight spaces, so I’m kind of looking at this as a challenge to try it without a lift. Now I just need to find a Sienna to borrow =)