Posted 01 July 2010 - 03:10 PM
I use them mainly to make wider tires than are available other than by special order from the silicone tire makers. I like as wide a tire as I can get to suit my needs. I use old worn down sponge tires with the big and full hubs such as made by JK, HTK, or Alpha on my 1/24 cars. This gives me at least a .450" inside diameter for inserts. I like them worn down to about .750" for rears or trimmed down to that size. Adjust for your needs by trimming. I make them about .030-.040" smaller than the desired finished size. That allows about a .030-.040" coat of silicone. I have found this brand of silicone to work the best so far: Permatex black silicone sealant available in 3 oz tubes at the local auto parts store.
I prepare the tires by truing to exact size on a tire truer of commercial or homemade type, or a handheld drill motor and sandpaper block. When truing, make sure they have a true tire shape with rounded sidewalls and a rounded edge to resist grabbing the slot or braid in corners. It also makes the silicone stick to the tire better and resist peeling at the edges. Very important point in keeping them intact for awhile while racing them. After truing them up, now you must clean them very well. I use lighter fluid and a clean rag. Wet them down several times and wipe off any truing dust or tire goop material, so the rag shows clean when done.
Mount them on a spare axle near the end so you can easily grip them by the axle without touching the tire.
Mount the tire and axle in a lathe chuck or use a small drill press or hand held drill motor, held in a vise to have control, of how they get worked on. Make sure the motor does not spin them too fast or you will not get the silicone to stick and get some thrown off in your face (messy).
Once mounted in the chuck, open the tube of silicone, and with a clean dry finger, apply a 1/4 inch long, ribbon of the silicone as it comes out of the tube to your finger and then rub it in vigorously into the tire surface working the first coat in firmly to get seated it into the tire surface completely. It will take at least three to four applications of the same size amount of silicone to coat the tire well enough to build up a coating of at least .030 -.040" to come to the desired diameter of the tire.
When all coats are applied, clean your finger off well. I recommend a finger wetted with spit or (water) to be applied to the tire surface to work the silicone now on the tire surface into a smooth and complete coating. Especially working it down around the sidewalls to the rim. Make sure the sidewalls have a good coating front and rear.
The spit or water will keep it from sticking to your finger, so it can move the silicone around where you want it. When it looks good to you. Stop and get out a smooth flat surface such as the recommended Lexan sheet, 1/8 inch thick by at least 6-8 inches long. A piece of glass or a mirror will work as well. The sheet is then wet with water or (spit) and applied to the tire surface either by bracing the bottom side against the nearest hard surface, or as I prefer just hand-hold it against the tire surface and lightly press against the tire to make a good true flat surface. If you press too hard, you will run the silicone over the edge too far and have to work it back to the center again. This will take some practice to get it the way it looks best. If you get a sharp edge, wet your finger again and work the sharp edge back to the middle and use the sheet again to flatten and true again.
Once it looks right and true, watch the run-out, remove the axle and wheel from the chuck without touching the tire. Place the axle end, in an upright position in a hole drilled in a block of wood so it will stand upright by itself. Then when both, or as many as you have done, are mounted in enough holes, place the block of wood under a 60 watt lamp to warm them up for at least three hours to dry the silicone out. When dry, you can true the tire up, or just run them in. I find as I get practice at it I can get my tires to within .010" enough for racing purposes.Many of them are ready to run right after drying and just a few laps of tracktime will true them right up.
I realize this is quick and dirty, so if you have questions please ask and we will try to give an answer. It looks easy but does take some practice. Don't attempt this on wheels with inserts as the silicone will tend to wrap around the sidewalls and get into the inserts and get messy. On plain wheels it is easy to clean it out and then add the inserts after.
Lucks of luck,I have some of these tires still around and usable from some I made in the middle '80s. The silicone tends to seal the sponge rubber from the air and does not allow it to dry out as it normally does. They stay soft for quite a while while fully coated.
Later on I found I could make a fixture out some old aluminum I had access to. It fit in my lathe and does make it very easy to get the tire diameter very close to each other using the lathe hand dials. I then mounted a piece of Lexan in it to smooth the silicone out and and keep it very close to level from side to side.
Requiescat in Pace
Posted 01 July 2010 - 03:23 PM
I realize this was originally posted elsewhere, but that doesn't matter one bit. Thanks for bringing it over.
Never forget that first place goes to the racer with the MOST laps, not the racer with the FASTEST lap
Posted 01 July 2010 - 04:03 PM
Thanks for taking the time to do it.
"Drive it like you're in it!!!"
"If everything feels under control... you are not going fast enough!"
Some people are like Slinkies... they're really good for nothing... but they still bring a smile to your face when you push them down a flight of stairs.
Posted 01 July 2010 - 06:08 PM
Posted 02 July 2010 - 09:25 AM
I've been coating tires for close to 10 years now for home use. The base tires does need to be nice and true like a Hudy produces. After that it's just getting the silicone on reasonably smooth.
Tires have good grip without the harshness that solid silicones have. And when the silicone wears through, just peel off the excess and re-coat. New tires cost maybe a dime each!
Silicone coated tires are very vintage correct also. These types tires were avaiable from as early as 1965.
Posted 02 July 2010 - 10:46 AM
Gary, the excess rubber can be cleaned out of the wheel with a sharp #11 X-Aato blade run around the edge of the rim at about a 45 degree angle. It will peel the excess off nicely
That last photo embelishes on the original article. This is one of the best, most useful how-to articles ever. Thank you, Larry! One question on these. When you finish your tires, what method do you use to get the silicone that runs over the edges of the rims off? I peeled some off but pulled a little off the rubber tire. I figure you must have a better way, probably like not being a sloppy craftsman in the first place.
I don't recommend using these tires on a commercial track as they will rub off the spray glue on the track in a short time. leaving foam tire users a slippery track and they tend to get upset with you using them.
On a home track they work fine and will work well on most surfaces except on a real dusty track.
Requiescat in Pace
Posted 02 July 2010 - 10:53 AM
Hello my name is Barney and I was... I am addicted to glue, magnets, and wings... I have been clean and sober years now... NOW I'm hooked on 1/32 club track racing! Dang!
"Even if you're on the Right Track, you'll get run over if you just sit there!"
If you remember screw-on braid, motors that look like padlocks, that dang fuse wire in Cox controllers, "hand" painted bodies, the very first can motors from Mabuchi, and the smell of wintergreen then you are OLD!... like me!
Enjoy life! Race Slot Cars and read SlotBlog!
Posted 02 July 2010 - 01:28 PM
Well, Harv, I find that my spit works best for me. I don't like to use chemicals on things anymore. I gave up on lacquer paints some years back As I don't want to breathe that stuff anymore. At 73 I don't need to hurt my lungs anymore. Use what you like, if it works for you.
Hey Larry have you ever used Naptha to smooth the tires? That's what I use to move the rubber and then use acetone on the final pass. I find it works better than water for me.
Requiescat in Pace
Posted 02 July 2010 - 02:21 PM