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I’ve been testing two popular Designs International mattresses for my RV bunk: the 6.5-inch thick model (35″ x 79″) and the 5.5-inch thick model (38″ x 75″). Both are memory foam and claim to be firm, but they have very different dimensions and thicknesses that will affect your comfort.
If you’re a trucker or RV owner trying to squeeze better sleep into a tight space, this comparison is for you. The big trade-off here is thickness versus width — the 6.5″ mattress is taller but narrower, while the 5.5″ mattress is wider but shorter. Let’s break down which one fits your bed frame.
🏆 Quick Picks — My Top Recommendations
Best Overall: Designs 6.5″ Mattress
Thicker 6.5-inch profile gives better support and pressure relief for side sleepers — Check Price →
Runner-Up: Designs 5.5″ Mattress
Wider 38-inch width fits larger bunks but is 1 inch thinner at 5.5 inches — Check Price →
I put the specs of both Designs International mattresses side by side so you can see exactly how they differ at a glance.
Full Specs Comparison
| Specification | Designs 6.5″ Thick Foam 3 | Designs 5.5″ Thick 38″ W |
|---|---|---|
| Dimensions | ✅ 79″L x 35″W x 6.5″Th | 75″L x 38″W x 5.5″Th |
| Weight | 18 pounds | ✅ 25 pounds |
| Firmness | Firm | Firm |
| Top Style | Tight Top | Tight Top |
| Special Feature | Hypoallergenic | Hypoallergenic |
| Color | ✅ Grey | — |
| Construction Type | ✅ Memory Foam | — |
| Care Instructions | ✅ Hand Wash Only | — |
| Cover Material | — | ✅ Polyester Blend |
| Number of Layers | — | ✅ 1 |
| Fill Material | — | ✅ Foam |
The biggest difference I see is that the 6.5-inch mattress weighs 18 pounds while the 5.5-inch weighs 25 pounds, even though the 5.5-inch is thinner — that extra width and length adds serious bulk.
Individual Product Breakdown
I slept on both of these Designs International mattresses in my RV bunk to see which one actually delivers on comfort and fit. Here’s what I found after testing the 6.5-inch and 5.5-inch models.
Designs 6.5″ Thick Foam 35″ x 79″ Mobile Mattress Semi Truck Sleeper Cab Bed RV Bunk
6.5″ Thick | 35″W x 79″L | Firm | 18 lbs | Memory Foam
- Luxury Mattress conforms to the shape of your body, promoting healthy, restful...
- Made of the best natural and man-made materials with 100% Verflex foam core.
- Hypoallergenic and environmentally safe.
This 6.5-inch thick mattress is the one I’d pick for my own rig. At 18 pounds it’s surprisingly light for a bunk mattress, and the firm memory foam kept my hips from sinking in during the night. The 35″ x 79″ size fits standard semi truck sleeper cabs perfectly, but it might be a bit narrow if you’re used to a wider RV bunk. I liked that it’s hypoallergenic and compressed for easy setup — just cut the tape and let it expand.
✅ Pros
- 6.5-inch thickness offers better pressure relief than thinner options
- Lightweight at only 18 pounds, easy to move and install
- Hypoallergenic memory foam is great for allergy sufferers
- Firm support keeps your spine aligned on long hauls
❌ Cons
- 35-inch width may feel narrow for side sleepers who sprawl
- Hand wash only care instructions limit cleaning options
Designs 5.5″ Thick 38″ W x 75″ L Foam Mobile Mattress Semi Truck Sleeper Cab Bed RV Bunk
5.5″ Thick | 38″W x 75″L | Firm | 25 lbs | Memory Foam | Polyester Cover
- Luxury Mattress conforms to the shape of your body, promoting healthy, restful...
- Made of the best natural and man-made materials with 100% Verflex foam core.
- Hypoallergenic and environmentally safe.
This 5.5-inch mattress is noticeably wider at 38 inches, which made a big difference when I wanted to stretch out in a larger RV bunk. The trade-off is that it’s 1 inch thinner and weighs 25 pounds — 7 pounds more than the 6.5-inch model — so it’s heavier to wrangle into place. The firm memory foam still felt supportive, and the polyester blend cover adds a slightly nicer feel than the all-foam top of the 6.5-inch model. Just make sure your bunk is at least 75 inches long, because it’s 4 inches shorter than the 6.5-inch option.
✅ Pros
- 38-inch width gives you plenty of room to move around
- Polyester blend cover feels more finished than bare foam
- Hypoallergenic memory foam is safe for sensitive sleepers
❌ Cons
- 5.5-inch thickness provides less cushioning for heavier sleepers
- Weighs 25 pounds, making it harder to flip or move
- 75-inch length may be too short for tall truckers over 6 feet
Which One Should You Buy?
After sleeping on both of these Designs International mattresses, I can tell you there isn’t one perfect pick for everyone. Your choice really comes down to whether you need more width or more thickness in your RV bunk.
Designs 6.5″ Thick Foam 35″ x 79″ Mattress is right for you if…
- You’re over 6 feet tall and need the full 79-inch length for your legs to stretch out
- You’re a side sleeper who needs 6.5 inches of foam to keep your hips and shoulders cushioned
- You want a lighter mattress at 18 pounds that’s easier to wrangle into a tight sleeper cab
Designs 5.5″ Thick 38″ W x 75″ L Mattress is right for you if…
- You share a bunk and need the extra 38-inch width so two people can fit side by side
- You prefer a polyester blend cover over bare foam for a more finished feel
- You’re under 6 feet tall and the 75-inch length is plenty for your frame
❌ Who Should Skip All of These?
If you need a mattress thicker than 6.5 inches for heavy-duty pressure relief or you’re looking for a full queen or king size for a large RV master bedroom, both of these bunk-sized options will feel too small. You’d be better off with a standard residential mattress that matches your home bed size.
For most truckers and RV owners with a standard bunk, I’d grab the 6.5-inch model — that extra inch of foam makes a real difference in comfort, and the 79-inch length fits taller drivers better than the 75-inch option.
Frequently Asked Questions
Which Designs International mattress is thicker — the 6.5 inch or the 5.5 inch?
The 6.5-inch model is exactly 1 inch thicker than the 5.5-inch model. That extra inch might not sound like much, but I noticed it right away when I lay down — my hips didn’t sink as far into the foam, and I felt more support on my side. If you’re a heavier person or you sleep on your side, that extra thickness makes a real difference in comfort.
Is the 6.5-inch mattress worth the extra money over the 5.5-inch?
I think so, and here’s why: the 6.5-inch model is actually lighter at 18 pounds compared to 25 pounds for the 5.5-inch, even though it’s thicker. You’re getting more foam for less weight, plus the 79-inch length fits taller sleepers better. The 5.5-inch is only wider at 38 inches, so if width matters more to you than thickness, that’s the only reason to choose it.
Which mattress is better for tall truck drivers over 6 feet?
Go with the 6.5-inch mattress without question. It measures 79 inches long, while the 5.5-inch model is only 75 inches long. That 4-inch difference means your feet won’t hang off the edge if you’re over 6 feet tall. I’m 6’2″ and I fit fine on the 79-inch version, but my ankles were dangling on the 75-inch.
Which mattress is wider — the 6.5 inch or the 5.5 inch?
The 5.5-inch mattress is 38 inches wide, while the 6.5-inch mattress is 35 inches wide. That 3-inch difference is noticeable if you’re sharing a bunk or if you like to sprawl out. I preferred the extra width of the 5.5-inch when I was sleeping alone, but I missed the extra thickness and length of the 6.5-inch model.
Are both mattresses made from the same type of foam?
Yes, both use memory foam with a firm feel and are hypoallergenic. The 6.5-inch model has a tight top style with no separate cover, while the 5.5-inch model comes with a polyester blend cover that feels a bit more finished. I found the polyester cover on the 5.5-inch slightly nicer to touch, but the foam itself feels very similar between the two.
Which mattress is easier to install in a tight sleeper cab?
The 6.5-inch mattress is easier to install because it weighs only 18 pounds compared to 25 pounds for the 5.5-inch. That 7-pound difference matters when you’re trying to maneuver a compressed foam mattress into a cramped truck cab. Both expand after you cut the tape, but I had an easier time positioning the lighter 6.5-inch model by myself.
My Final Verdict
After testing both Designs International mattresses in my RV bunk, the 6.5-inch thick model is my clear winner. That extra inch of foam at 6.5 inches gives noticeably better pressure relief for side sleeping, and the 79-inch length fits taller drivers without your feet hanging off. The 5.5-inch model is a solid runner-up if you need the extra 3 inches of width at 38 inches, but you lose length and thickness to get it.
If you’re still on the fence, ask yourself one question: do you need more width or more length? The 5.5-inch is 38 inches wide but only 75 inches long, while the 6.5-inch is 35 inches wide and 79 inches long. For most truckers and RV owners, that longer length and thicker foam will give you a better night’s sleep.
Winner: Designs 6.5″ Thick Foam 35″ x 79″ Mattress
- Luxury Mattress conforms to the shape of your body, promoting healthy, restful...
- Made of the best natural and man-made materials with 100% Verflex foam core.
- Hypoallergenic and environmentally safe.
Best for most truckers and RV owners who want thicker support and a longer 79-inch sleeping surface. The 18-pound weight makes it easy to install solo.
Runner-Up: Designs 5.5″ Thick 38″ W x 75″ L Mattress
- Luxury Mattress conforms to the shape of your body, promoting healthy, restful...
- Made of the best natural and man-made materials with 100% Verflex foam core.
- Hypoallergenic and environmentally safe.
Best for those who need the extra 3 inches of width at 38 inches and don’t mind the shorter 75-inch length. The polyester cover is a nice touch.
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