Rhino ramps filled with structural foam?

Structural foam is different from general purpose spray foam
My rigid plastic ramps, are well pretty rigid.

Adding the strongest foam (post hole foam?) -

A) Will it add compressive strength?
B) Will it add shear strength?

Maybe I should ask my brother. But for now ask AI.

I asked Chat GPT. The answer was really good. I am an AI doubter. It goes into mechanisms.

Short answers:
A) Yes — filling voids with a high-density, closed-cell foam will increase compressive capacity of the ramp assembly overall.
B) Partially — foam adds some shear resistance by supporting local faces and reducing stress concentrations, but it provides far less shear strength than a structural core (e.g., solid plastic, metal ribs, or structural honeycomb) and won’t appreciably increase the ramp’s ability to resist sliding or large transverse loads.
 
I guess like most here with Rhino Ramps, if you really want them, get the 8000lb axle capacity ones, for a much lighter vehicle and store them properly, they will be fine for a long time.
I've learned that lots of plastic doesn't like being stored in my steel roof shed, with some what I thought were well sealed solvents and gas containers, at higher temperatures in the summer. Wood and steel stored in the same shed doesn't degrade at all.

Simplest, toughest, cheapest, and longest lasting is just softwood.

The race ramps are nice and light and plenty strong when new, but they don't actually say what they are made of? I assume polyurethane foam which is fine for most automotive fluids, but might dissolve with acids or solvents used for body work? And they rely on a coating to keep the internal foam protected which depending on your usage, the coating may not last.
Also don't use them on your driveway, or maybe even in your garage on a hot day, 120F is their max temperature for usage, and 150F for storage.
 
I guess like most here with Rhino Ramps, if you really want them, get the 8000lb axle capacity ones, for a much lighter vehicle and store them properly, they will be fine for a long time.
I've learned that lots of plastic doesn't like being stored in my steel roof shed, with some what I thought were well sealed solvents and gas containers, at higher temperatures in the summer. Wood and steel stored in the same shed doesn't degrade at all.

Simplest, toughest, cheapest, and longest lasting is just softwood.

The race ramps are nice and light and plenty strong when new, but they don't actually say what they are made of? I assume polyurethane foam which is fine for most automotive fluids, but might dissolve with acids or solvents used for body work? And they rely on a coating to keep the internal foam protected which depending on your usage, the coating may not last.
Also don't use them on your driveway, or maybe even in your garage on a hot day, 120F is their max temperature for usage, and 150F for storage.

Didn't know about the 120 degree limit. I use flat stoppers, sometimes out in my pole barn.
Don't think it ever got to 120, but easily over 100 here and there.
 
I bought Rhino ramps when they were first released making my pair over 25 years old. I store them inside the garage and have not had an issues to this point.
 
Ran across what could have been some amazing ramps - saved weight and all - but look at the bevel cuts LoL

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I was thinking of buying some rhino ramps and filling the void with the foam used to set fence posts and other things like it. My intention is that it would add additional structural integrity to the ramps. My only problem is that I can't find the compressive strength of this type of expanding foam.

Good, bad, ridiculous idea?
OP, I have a bunch of plastic ramps all around the “compound” sometimes holding up a vehicle for years at a time in the AZ heat and sun. Some are Rhino some are brand x. I am much more concerned about a steel jack stand failure that any of these. I’ve had some of these ramps for 20 years plus and never a fault or crack. They have deformed sometimes due to operator error. I like your idea but I would be hesitant to do it because of creating stress risers and causing chemical damage, unintentionally. Just use ‘em.
 
OP, I have a bunch of plastic ramps all around the “compound” sometimes holding up a vehicle for years at a time in the AZ heat and sun. Some are Rhino some are brand x. I am much more concerned about a steel jack stand failure that any of these. I’ve had some of these ramps for 20 years plus and never a fault or crack. They have deformed sometimes due to operator error. I like your idea but I would be hesitant to do it because of creating stress risers and causing chemical damage, unintentionally. Just use ‘em.
Thanks. I was looking at the reviews of these ramps and I was surprised by the out of the box failures in lieu of the "these are old and finally cracked".

I'm just trying to convince myself that they're safe enough to invest in doing my own oil changes over the objections of family. I have zero room for errors here. If they crack I'll never have this opportunity again.
 
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I think if you buy them and use them, you will develop confidence in them. I’m surprised that there are any reviews that are negative. Mine are stored in the sun in Arizona subject to UV, ozone, etc., and they have not been a problem. Even hoisting up one end of an Excursion multiple times. If you’re concerned, maybe be back them up with jack stands. When I’m doing four wheels in the air in my driveway, I will use the jackstands, but put the ramps underneath the body also just in case something drops. I trust the stands much less than the ramps. I think you will find them to be very good to use in the long run.
 
I like my Rhino Ramp, but I don't own pickups or SUVs only things below 4000 lbs like wagons and cars. I trust it better than home made wood ramp because they have a less likely chance of me running over it and take up less space when stacked in storage. If I fill it with foam that defeats the purposes and I might as well just use jack stands.

I am more worried about things tipping over sideway than the plastic bending and failing. I still put up stands nearby as insurance.
 
OP, I have a bunch of plastic ramps all around the “compound” sometimes holding up a vehicle for years at a time in the AZ heat and sun. Some are Rhino some are brand x. I am much more concerned about a steel jack stand failure that any of these. I’ve had some of these ramps for 20 years plus and never a fault or crack. They have deformed sometimes due to operator error. I like your idea but I would be hesitant to do it because of creating stress risers and causing chemical damage, unintentionally. Just use ‘em.
I agree about some metal will crack instead of bend. The same also goes for some plastics.

In the end the quality of the manufacturing is just as important as which one would be safer. A bad weld can turn a good material dangerous and unless I can see "if it fail where and how can it be" I would not trust it. I have seen enough photos about Harbor Freight jack stand's metal cracking and shattering that I wouldn't trust it better than a reputable brand plastic ramp or metal ramp.
 
I did a google search on spray foam compressive strength and the first hit was a Garage Journal thread that seemed pretty good.

Here is one reference: https://commercial.owenscorning.com/assets/0/144/172/174/c273fe0e-e0c8-4bb2-9ed3-6e3ba390a12c.pdf

Depending on the spray foam, you might have an ultimate strength of up to 100 psi, but IMO the foam will be so much less stiff than the plastic that it won't practically share much of the load at all.

I think reinforcing your ramps with foam is a pretty bad idea.
 
Been using Rhino plastic ramps for decades. Like everything else, they just need to be used correctly.

I think the older Rhino Ramps, under the Blitz moniker, are hella lot stronger than what I'm seeing sold today.

I've had a set for 25+ years now and they've been great. These newer versions look like a house of cards.
 
I think the older Rhino Ramps, under the Blitz moniker, are hella lot stronger than what I'm seeing sold today.

I've had a set for 25+ years now and they've been great. These newer versions look like a house of cards.
Having done stress analysis on many injection molded plastic parts, I can say with confidence that plastic designs that look the strongest aren't always.
 
Having done stress analysis on many injection molded plastic parts, I can say with confidence that plastic designs that look the strongest aren't always.

I'm going on experience, not looks. The older ramps just seem to hold up better. Way too many stories, with pics, of the newer version collapsing. No bueno IMO.
 
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