Big Rock Foam inserts bad?

[Papa_smurf]

I've searched about foam inserts; methods to remove tires in the oven, finding new inserts, etc. But I haven't found a thread describing how to tell if your inserts are bad.

After a session today I randomly squeezed a tire and it felt SUPER soft. So I squeezed them all and at least 2 of them felt like there was no foam in them at all. One of them felt like I would have expected - though not sure what exactly to expect considering its my first RC. I have ran a couple times on a local track when there were some decent puddles in some corners. Tires are stock (vented). Has my foam gone bad?

 

[SrC]

Once they get wet. They get moldy and rot. I've had foams that literally disintegrated to powder and came out like dust and powder from the vents.
Just drive them till they are done. And buy another set. Just this time, drill a vent, 1/8" holes in 2 outer places of the tread 180 degrees apart and seal off the inner wheel vents with Duct tape or similar. Do this when they are new. The Foams should last longer. Open cell foam does get damaged with water. Closed Cell foams do not. FWIW. Closed cell foams are not found on most MT wheels. Just on Track wheels self built and with some Crawler tires as upgrade foams.
Venting at the outer tread lets the water and dirt evacuate with the tires rotation. Centrifigal force. I avoid the wet for this and other reasons. Tires cost too much. Bad foams create a very unbalanced tire at some point. The foams will bunch up internally, unevenly. This can contribute to blow outs and tire shredding at some point also. Been there.
FWIW. I rarely break down a tire any more. Not worth my time. May work for you. I boil the wheels/tires in water. They never come apart clean enough however. Should have fresh foams of the correct size to rebuild them. Or it is not worth all the effort. Just me.
When regluing, use a good Hobby grade CA like BSI IC-2000 rubberized CA.

 

[Paul777]

If you're lazy but have patience I have found that sealing them in a zip lock bag (freezer bag) with 50ml of acetone for a few days works, they pop right off nice and clean. I use a tub to prop it up so the wheel isn't actually sitting in the acetone just in the vapour. The foams in the Big Rock don't last long if you run in the wet, venting tyres and spin drying them after a run helps but the foam Arrma uses is terrible.

 

[SrC]

I find that acetone can ruin an otherwise good set of foams too.
I balance my wheels when they are new, and after at least one run. The intial run of new tires helps the foams to center out evenly inside the tire. Then balance.
Poor balance can blow out a tire prematurely. I can rarely wear out tires at the tread before they blow out or shred apart. True for most non belted tires. Because of Ballooning and all. Always check the tires beads after/before runs. Touch up with a good tire CA as needed. You can prevent much blow outs this way. Check the beads even when brand new. Many tires are made poorly with little CA. Poor QC. No matter the brand. PL and the rest. Pull on the beads hard and you may see areas that can use more CA. They will last much longer down the road. Leave nothing to chance with Tires. They are a costly part of RC. It's very easy to brick a new tire within 5 minutes. Been there. It sucks.

 

[Paul777]

I find that acetone can ruin an otherwise good set of foams too.

Absolutely, seems fine for the wheel and tyres (although it will strip the silver from the old big rock wheels), but only do it if the foams need replacing. If you are looking to replace tyres but want to keep foams (I've never had an Arrma foam last that long but I guess if you run in the dry you might) cut the tyre to get the foam out first.

 

[SrC]

^^^, Arrma has 2 different foams across their lines.
The Black foams are the best. The Whites are the junk. Softer also. Seems the 3s lines get the Blacks for the most part. Not 100% sure though. Hard to source just the Foams for all the wheels. PL used to have many different foams available. Not lately. Since HH bought ProLine, maybe. Wheels/Tires are mostly premounts these days. I like the 4s line BF LP's for my 6s rigs. Least ballooning and with same BF tread. Lower profile. Available as premounts or separate wheels and tires/foams. If you want to build a set yourself. I've always had best results building my own new wheels. My own CA etc. No skimping with the CA when I do them. Factory assembles these MT tires so fast. QC suffers. Just me.
Tires are a big profit maker for RC brands. They love selling them. We are stuck having to pay hard for them. Can't drive a rig without its shoes.
They know this, and make it very profitable for themselves. I feel the markup is crazy high for what you get. ( with cheap crap for foams)
FWIW.

 

[Paul777]

I made up new foams for my copperhead2s on my Noto because you can't seem to buy the foams and the tyres were hardly worn. Doing this costs about £1 per wheel. So far they are working well for general bashing and have lasted a lot longer than the stock ones did - winter will be the real test though. First pic is the only foam that wasn't just dust. The new ones are made from 2 layers of closed cell polyethylene self-adhesive foam with sticky sides stuck together wrapped round with duct tape. Being closed cell they don't absorb the water like the stock one do and shouldn't rot. They are firmer/denser than the originals but work well enough for me. I do balance the wheels once they are all fitted.

 

[SrC]

Nice.
Takes much patience to get them right.

 

[Papa_smurf]

I made up new foams for my copperhead2s on my Noto because you can't seem to buy the foams and the tyres were hardly worn. Doing this costs about £1 per wheel. So far they are working well for general bashing and have lasted a lot longer than the stock ones did - winter will be the real test though. First pic is the only foam that wasn't just dust. The new ones are made from 2 layers of closed cell polyethylene self-adhesive foam with sticky sides stuck together wrapped round with duct tape. Being closed cell they don't absorb the water like the stock one do and shouldn't rot. They are firmer/denser than the originals but work well enough for me. I do balance the wheels once they are all fitted.
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This is awesome. Might have to order a new set of wheel and attempt this on my stock set that is messed up!