What I was wondering is there anyway to pour these truck tires so they aren't solid like some people have told me or is there any way to pour them to look like the originals do, or is it what them other people have told me the only way I got to pour them?

Thank You Very Much for your time
Kerry

The only way to cast a hollow tyre is if you are willing/able to create a 4-5 piece mold. Speaking from experience this isn't much fun and a real pain in the b___t.
The only other way is cast each half seperately (as hollow) then join, which really runs the risk of misalignment or sizing differences (depending on what type of resin used).
HTH

Roger.

Good question....I'd add how does one cast a rubber tire?{as in not hard resin}...do we use a rubber mold or is a mold for such a thing hard resin?
Reason I ask is I need to make a full set of the paystar lug tires for a US army resin cab conversion I have...the paystar kit comes with 8 rear "lug" tires and 2 front flotations...I'll need 10 lug tires and a spare. Rahter than swipe from another kit I'd like to cast my own full set in soft rubber...

I don't remember if it's Micro Mark or Alumilite that makes a compound for casting rubber tires, but it can be done. Making the hollow mold would be the hard part.

Jesse

Just a thought

I used basic black silicon mastic from my local B & Q hardware store to replicate a set of missing tyres for one of my Massey Ferguson tractor in 1/24 scale.

The silicon was injected into my two part mold of plaster. They came out a bit crude looking but that I think was more down to my lack of skill and materials for the mold I made of the originals. But hey ,,,,,,,,,,,,,,,,, I started off with a tractor with no tyres !!!!!!

My set fitted but I was working in 1/24 with a lot of wriggle room compared to 1/35.

Nige

Maybe you could try to make copies using dental grade plaster then cut out the hubs to leave the tyres to cast molds from.

Nige

Smooth on has some castable softer resins and rubbers that are black or can be tinted. I have some to try Just haven't had the time. (it's for a 1/35 scale project)

IMHO - avoid hard molding compounds i.e. plasters/resins, the reason being -
a. You have to be able to remove the master pattern without damage to the mold and later be able to remove X number of castings without damage to the mold.
On the ones I made I simply used a firmer silicone for the mold (normally used with white-metal figure casting) and ALWAYS remember to use release agent.
While I have only done two sets of soft tyres (both for other people) here's my thoughts/observations and a few things to consider:
1. Air bubbles/pockets forming during the casting process. The easiest way to avoid this problem is to vacuum cast, however not everyone has a vacuum chamber sitting around, SO consider compression casting, which is pouring each half of the mold (assuming you are using a two piece mold!) till just level with the top (note don't cut pour plugs or venting chambers in the mold) and allow to just start setting up/curing then with some fresh mix, slightly overfill one side then join the two halves of the mold and gently compress which will bond the two halves and eliminate any air bubbles/pockets. The downside of this method is the "flash" that needs trimming and some componds don't bond very well once they reach a certain setting point .
2. Remember that air bubbles/pockets cannot be satisfactorily filled once the casting has cured (due to the flexing so the downfall of soft tyres).
3. Be careful with the choice of silicone/resin for the actual castings. Probably not as much an issue now but some of the older silicones tended to badly leach silica over a period of time and then become unstable. If you place a silicone mold on some bare wood for 24 hours, when you remove it there will be a stain which is the silica being drawn out of the mold.
So, in summary I personally consider soft tyres a novelty and are more hassle than they are worth plus also more expensive to produce than standard resin tyres.
NB. I use the compression casting method with standard resin = no pour plug to have to mess about with, plus I also vacuum both the silicone and the resin to limit any air bubbles.

Incidentally from a rivet counters perspective (not), from memory those Ertl tyres are a tad skinny for military bar-tread, plus aren't they a hard vinyl ?.
HTH

Roger.

Roger - Yeah, the paystar lug tires are vinyl. I had thought about using regular resin but it's just something I'm not to happy with in it's use for tires...maybe I've done too many box kits with soft tires?!
Nige - what was the finish on your palster mold?...smooth, alittle grainy...alot grainy...? One thing I learned long ago in my limited casting days was that if your mold or master wasn't up to snuff, then your castings won't be either....even the difference of flat, gloss, or semi gloss paint on the master showed on the cast piece.
Matt, maybe give that stuff a try not only for us but for the review too{yeah, like you've got nothing else going on....I know!}

I, myself, wouldn't monkey with "hollow" tires{no offence Kerry}...I just don't think the effect would show enough for the hassle. One could take a given tire and add some bulge to it, then cast that, to mimic a loaded tire. Don't forget that "nearly" any medium can be used for casting..clay, brass, sealed wood{unless you want a grain effect - then don't seal it}, plastic, wax, or any combo of the list...so long as it won't melt when covered with mold material, you should be fine.
My mold making experiance is limited to a few "squash" molds{2 halves}, "solid plug"{amt mack noses for lil mack switchers} and "flat sheet" casting for sides of electric street cars or freight cars. I've always wanted to try a "plunge" mold set up...for example - if making an old mack nose{whole hood and radiator}, instead of a casting solid piece, I'd insert some kind of plug into the mold after pouring to hollow it out....you use less resin this way and make the part lighter.

all,
Here's a link to an article that covers both aspects of the questions posed (hollow tyres & rubber compound):
http://www.henribaigent.org/Wheels%20and%20Tyres/Wheels%20and%20Tyres.htm
Enjoy.

Roger.

I really appreciate all the answers I got from everybody, so on this kit I got from Micro Mark it says solid tires on it's directions so I better stick with that.
Thanks again everybody.