Why aren't tires in model kits made of rubber?

[RuffRuff]

They do sell black rubber style paint... I wonder if I could spray the tires with that.

 https://www.walmart.com/ip/Rust-Oleum-Rubberized-Undercoating/16816070?wmlspartner=wlpa&selectedSellerId=1122&adid=22222222227009664201&wl0=&wl1=g&wl2=c&wl3=61434227328&wl4=pla-88036067808&wl5=9060388&wl6=&wl7=&wl8=&wl9=pla&wl10=101593696&wl11=online&wl12=16816070&wl13=&veh=sem

[Ace-Garageguy]

They do sell black rubber style paint... I wonder if I could spray the tires with that...

NO. That's a heavily textured product for exactly what it says...UNDERCOATING.

[RuffRuff]

They do sell black rubber style paint... I wonder if I could spray the tires with that.

 https://www.walmart.com/ip/Rust-Oleum-Rubberized-Undercoating/16816070?wmlspartner=wlpa&selectedSellerId=1122&adid=22222222227009664201&wl0=&wl1=g&wl2=c&wl3=61434227328&wl4=pla-88036067808&wl5=9060388&wl6=&wl7=&wl8=&wl9=pla&wl10=101593696&wl11=online&wl12=16816070&wl13=&veh=sem

Okay, Ace-Garageguy that was the wrong stuff. I meant to post something more along the lines of this stuff - 

[The Junkman]

My question is why don't manufacturer's mold their tires in polystyrene?  No issues with chemical misadventures, certain to fit the wheels enclosed in the kit, no issues with incompatibility with paints.

[Daddyfink]

Styrene tires would work great, but, I am sure the kids today would not know how to paint a tire black. 

[peteski]

Actually, all the Japanese-made model car kits I have (Tamiya, Aoshima, Fujimi, Otaki, etc.) have tires made from rubber. Satco tires were also rubber (Japanese-made). They even smell like rubber!  But just like real rubber, after about a decade of being exposed to air, the surface starts to deteriorate and it hardens a bit too.

Why are tires molded using soft materials? I suspect that has something to do with being able to demold them from the mold cavities with all the sidewall details, tread and sometimes hollow center on a single-piece tire. If they were hard plastic they would never come out of the mold.  There are companies (mostly 1:35 military vehicles) that make tires out styrene. But to get the same level of detail as the soft tires, those hard plastic tires are made up from a sandwich of several pieces. Usually each sidewall is a separate piece and then there are several rings with the tread detail stacked between the sidewalls.  And they have to be painted to look like tires.

[Brian Austin]

They could mold them in black styrene.

 

:-P

[peteski]

26 minutes ago, Brian Austin said:

They could mold them in black styrene.

 

:-P

And they would look like they are made from black styrene. They are molded usually in neutral colors (like gray or beige) because that is what military modelers prefer and they are on the same tree as other parts.  But even if molded in black , they would still need to be painted to properly represent the color and surface sheen of rubber tires.

Edited November 27, 2017 by peteski

[Richard Bartrop]

If the styrene tires they put in the Italeri classic cars kits are anything to go by, they're better off sticking with vinyl or neoprene.

Edited November 27, 2017 by Richard Bartrop

[Junkman]

10 hours ago, Daddyfink said:

Styrene tires would work great, but, I am sure the kids today would not be allowed to buy the rubber coating spray necessary to paint them. 

EFA

[Brian Austin]

11 hours ago, peteski said:

And they would look like they are made from black styrene. They are molded usually in neutral colors (like gray or beige) because that is what military modelers prefer and they are on the same tree as other parts.  But even if molded in black , they would still need to be painted to properly represent the color and surface sheen of rubber tires.

And black vinyl for the most part looks like...black vinyl.  :-)

[Daddyfink]

[peteski]

9 hours ago, Brian Austin said:

And black vinyl for the most part looks like...black vinyl.  :-)

Well, the rubber tires in Japanese kits have a correct look. But yes, vinyl tires don't look very realisitc. But little rubbing using scouring poweder or some Dullcote makes them look like rubber. And of course if one models a car at a show with shined-up tires, shiny vinyl works just fine.

[Flat32]

For many years my company has been producing 1:1 snowplow light housings that we make with black TPR (thermoplastic rubber).  It is an injection material, not vulcanized with exactly the look and feel of rubber.  I suspect it could work quite well for car model kit makers.  Look at Gillette disposable razor handles for an example of what I believe is TPR.

I'm investigating making my own tires by casting and I'm certain soft black RTV material or polyurethane is available from Alumilite  or Smooth-on.  There are also 3D printable soft and flexible materials, but I don't think good enough for tread and sidewall markings details.

[Flat32]

Polytek urethane looks worth investigating too.

[peteski]

On 12/1/2017 at 6:05 AM, Flat32 said:

 

I'm investigating making my own tires by casting and I'm certain soft black RTV material or polyurethane is available from Alumilite  or Smooth-on.  There are also 3D printable soft and flexible materials, but I don't think good enough for tread and sidewall markings details.

Fireball Resin makes several types of tires cast in soft (urethane?) rubber material.

[Flat32]

2 hours ago, peteski said:

Fireball Resin makes several types of tires cast in soft (urethane?) rubber material.

I know they do.  Just not what I need to fit my rims.  I suppose you could say I want a real tire at 1:25.   I see no reason why we can't have Danbury Mint quality level spoked wheels on the beautifully hand crafted models I see on the forums.

[peteski]

18 minutes ago, Flat32 said:

I know they do.  Just not what I need to fit my rims.  I suppose you could say I want a real tire at 1:25.   I see no reason why we can't have Danbury Mint quality level spoked wheels on the beautifully hand crafted models I see on the forums.

Fireball Resin tires are depict tires on modern vehicles. So you are planning on making tires for antique cars?  As far as as the diecasts from Danbury or Franklin Mints go, I have couple Danbury Mint '30s cars and I don't consider their spoke wheels to be particularly well made.  The spokes are fairly out-of-scale molded plastic. Maybe you've seen some that have photoetched spokes?  Those look much better, but the best ones are hand-laced using wire.

[Flat32]

 

 

Danbury '32 roadster on right, molded plastic.  Danbury '32 3 window coupe on left, real wire spokes.

[peteski]

18 hours ago, Flat32 said:

Danbury '32 roadster on right, molded plastic.  Danbury '32 3 window coupe on left, real wire spokes.

Fair enough. I'm not a die-cast model collector and I have never seen any of the "Mint" models with nice real wire spokes like that.

[Casey]

On 11/2/2010 at 12:08 PM, Jon Cole said:

What tire melt?

 

http://images116.fotki.com/v700/photos/5/54765/228091/3Timehastakenitstollonthetires-vi.jpg

 

http://images22.fotki.com/v820/photos/5/54765/228091/QQThisslickhasREALLYdecomposed-vi.jpg

While I have seen a handful of 1/16 Revell F/C tires deformed, I have yet to find one which has melted. The rear slicks were molded with relatively thin (much thinner than other scale slicks) sidewalls, so that may have been a major factor in their eventual collapse, too.

I think it was Ed Sexton who told me the place in Japan where Revell had these tires molded (presumably the same place since the early '70s when the 1/16 scale F/Cs debuted) was destroyed by the Great Tohoku Earthquake in 2011, so the 2014 Hawaiian Charger F/C reissue had all-new tires which were molded in China.

As for Revell semi-soft tires holding up over time, I doubt it can be explained by one issue or phenomenon, so what may have caused the total failure of one set may have left another set unscathed. Maybe it's just luck, too, but don't assume the tires in your kit are now useless-- check them to be sure.

Here are pics I took today of the Mikey Thompson Baja King tires included in the 1/16 Revell Chevy Off-Road Pickup kit (and it's later modified reissues), which was released in 1979. The first image is of the four tires still "sealed" (with two small staples) in the original bag:

 

 

They are still in good nick, fortunately. I have another set from a built model I bought a decade ago, not nearly in the same condition, unfortunately. I'll take and add some images tomorrow.

 

[Casey]

Here is another vintage set of the Mickey Thompson Baja King tires, this set is poorer condition. Multiple factors at play I think, but as shown further below, other 1/16 Revell rubber-like tires have fared just fine. 🤷🏽

 

Same tires, vastly different condition:

 

1/16 Revell Funny Car Goodyear front tires, still in good nick:

 

Same for these 1/16 Revell T/F dragster skinnies:

[Casey]

As mentioned earlier in this topic, a few companies have tried experimenting(?) with different methods and material to mold tires, but something's got to give-- literally. Either the mold itself (say, when using a silicone rubber mold) or the tire itself (see, Revell and others' "rubber-like" tires) needs to be able to flex and allow the tire to exit the mold without damaging the intricately shaped tread blocks, something which need to be done thousands of times in a production cycle.

MPC tried something with it's Swamp Buggy Jeep kit, using styrene slick halves (outer and inner), then requiring the builder to glue the ends of a "Thermo rubber" tread strip together, allowing it to dry/cure (did model kit glue really work for this?), then slipping the tread piece over the circumference of the slick to create an off-road style tire...I'll let you decide if that was realistic, effective, accurate, etc. This appears to be one of the earlier attempts by MPC to mate PVC and styrene, and while they molded other parts (seating surfaces, floor mats, snowmobile seats and treads come to mind) in the same flexible vinyl material, the idea never stuck, was abandoned, and doesn't appear to have ever been attempted since.

 

For the record I don't think this was a terrible idea, as it allowed for excellent tread block/lug detail, but the mating and blending of two very dissimilar materials seems to be the stumbling block. Maybe the more recent proliferation of water-based acrylic paints make this lees of an issue in 2022 than it was in 1970?

 

[Fabrux]

How about these tires? From a Heller/Humbrol/Bobkit truck kit. Seems to be rubber and they do fit fairly tight. Haven't decided what to attach them with yet.

[PatW]

Where I display my models on plexi shelves I have to put sheets of A4 size printer paper or the tyres stick to both glass and plexi-glass, so to me plastic tyres help. They can be painted black or sand to look as if they have been on the road. One kit I bought contacted me to warn about melting as other customers had to claim new sets of tyres due to partially melting and sticking to all manner of surfaces.