Speedrun Custom Wheels // 250+ MPH

[Jerold]

I’m just going to throw this out there two part polyurethane it comes in different density’s from hard to soft

I think this is very doable and could be inexpensive too in bulk. Polyurethane and plastic are cheap. It's pretty easy to buy 100mm skate wheels. They are mass produced and cost ~$10-15 each, which is cheaper than our current wheels. Let's say speed wheels cost $25/wheel but didn't explode over 200mph and lasted more than one run. It's much cheaper than the current solution. For us slow guys they would last a life time.

There are kits to cast Polyurethane resin at home and I "think" it will require a few things.

1. A hub to hold it
2. Mold for the wheel
3. Some way to true it and make it round.

If you are speed running, wider tires don't help. You really need light weight want pizza cutters, with a lot of tangential strength. Polyurethane can be stickier and/or harder than foam or natural rubber. Which means they can much narrower and symmetrical.

Something like this. I was thinking adding some holes in the outside cross beam so the rubber can flow into might make it a bit more sturdy, but it's a bit of work to do that in cad.

Prototypes, machine out the wheel with a CNC (I don't have). For bulk use injection molding. For the molds just need to create an top and bottom mold (also CNC). Then pour the rubber. True up on "lathe".

I think a symmetrical hub is the strongest, but if it's asymmetrical it would be super easy to mold.

 

[King blitz]

I think this is very doable and could be inexpensive too in bulk. Polyurethane and plastic are cheap. It's pretty easy to buy 100mm skate wheels. They are mass produced and cost ~$10-15 each, which is cheaper than our current wheels. Let's say speed wheels cost $25/wheel but didn't explode over 200mph and lasted more than one run. It's much cheaper than the current solution. For us slow guys they would last a life time.

There are kits to cast Polyurethane resin at home and I "think" it will require a few things.

1. A hub to hold it
2. Mold for the wheel
3. Some way to true it and make it round.

If you are speed running, wider tires don't help. You really need light weight want pizza cutters, with a lot of tangential strength. Polyurethane can be stickier and/or harder than foam or natural rubber. Which means they can much narrower and symmetrical.

Something like this. I was thinking adding some holes in the outside cross beam so the rubber can flow into might make it a bit more sturdy, but it's a bit of work to do that in cad.
View attachment 322813

Prototypes, machine out the wheel with a CNC (I don't have). For bulk use injection molding. For the molds just need to create an top and bottom mold (also CNC). Then pour the rubber. True up on "lathe".
View attachment 322814

I think a symmetrical hub is the strongest, but if it's asymmetrical it would be super easy to mold.

I always heard wider in the rear help with traction which helps in producing more speed

 

[SrC]

Wider wheels do contribute to more rolling resistance, so the wider contact patch to the ground can also work against you at some point. Scrubbing off speed, drawing slightly more amps.
Something one needs to consider when designing wheels. Wider wheels also create more centrifigal force away from the hub's centerline. Makes the wheel weaker at very high rotational RPM's. GRP's are generally narrower than Hoons for instance. A plus.
Being Zero offset wheels is part of the main problem, IMHO. Wheel Bead support is greater on the outside, way less on the inside/inner bead.

 

[Jerold]

I always heard wider in the rear help with traction which helps in producing more speed

Traction is good for the launch (drag racing) the corners (road racing). It's about the size of the tire contact patch. More contact patch more traction. In a straight line we need only enough to get going and keep it on the road.

Of course if it's a new design we could change them to what ever width or compound that works. In theory, larger contact patch means more friction. More friction means more power required. However, I doubt that the amount of power to over come friction will be anywhere near the wind drag.

My drawing is completely arbitrary dimensions. My thought was to use thinner wheels & tires, with less mass and rotational energy. The thinner wheel, keeps the risk of deformation down and less chance of scattering rubber everywhere. However, to your point, we still need to get up to speed, which may require more rubber.

I was thinking of punching holes in the wheel like this so the rubber "grabs" the wheel. Again a crude sketch.

I think some testing would answer a lot of questions.

 

[King blitz]

Traction is good for the launch (drag racing) the corners (road racing). It's about the size of the tire contact patch. More contact patch more traction. In a straight line we need only enough to get going and keep it on the road.

Of course if it's a new design we could change them to what ever width or compound that works. In theory, larger contact patch means more friction. More friction means more power required. However, I doubt that the amount of power to over come friction will be anywhere near the wind drag.

My drawing is completely arbitrary dimensions. My thought was to use thinner wheels & tires, with less mass and rotational energy. The thinner wheel, keeps the risk of deformation down and less chance of scattering rubber everywhere. However, to your point, we still need to get up to speed, which may require more rubber.

I was thinking of punching holes in the wheel like this so the rubber "grabs" the wheel. Again a crude sketch.

View attachment 322841View attachment 322842

I think some testing would answer a lot of questions.

All good stuff my friend..all good... I've been thinking alot on how we glue tires to rims ..so we glue the front lip and rear lip right ? So what if the whole tire got glued to the rim.? No foam inside so all tire gets locked down .maybey them holes might even help .glue can go inside the holes for a better byte..are foam inserts really even needed?I don't know .but with the foam inside then we can't glue the tire completely inside to the rim .I think ballooning also happens because the middle of the tire isn't held down .so at high revolution the tire balloons then eventually the glued sides just can't hold on enough and the seal let's go which cause them to pop / blow off what ever you wanna call it .I'm just saying just a thought.if the whole tire is glued down then it should have a better over all effect rather just the sides.i also wounder if foam tire was glued down in strips.maybey 3 or 4 thin strips of foam were glued on top of each other .then at the end light sand where the ends meet to feather it all off evenly.again just my crazy ass thinking ..but thoughts are where it starts.
More and more them hockey pucks are sounding real good

 

[Jerold]

All good stuff my friend..all good... I've been thinking alot on how we glue tires to rims ..so we glue the front lip and rear lip right ? So what if the whole tire got glued to the rim.? No foam inside so all tire gets locked down .maybey them holes might even help .glue can go inside the holes for a better byte..are foam inserts really even needed?I don't know .but with the foam inside then we can't glue the tire completely inside to the rim .I think ballooning also happens because the middle of the tire isn't held down .so at high revolution the tire balloons then eventually the glued sides just can't hold on enough and the seal let's go which cause them to pop / blow off what ever you wanna call it .I'm just saying just a thought.if the whole tire is glued down then it should have a better over all effect rather just the sides.i also wounder if foam tire was glued down in strips.maybey 3 or 4 thin strips of foam were glued on top of each other .then at the end light sand where the ends meet to feather it all off evenly.again just my crazy ass thinking ..but thoughts are where it starts.
More and more them hockey pucks are sounding real good

I was thinking that we just pour the resin over the rim and true it up with a tire lathe.

 

[wadedog]

I cut the hub out of a hoon I’m thinking about casting it in polyurethane just thinking about it

 

[SrC]

I was thinking that we just pour the resin over the rim and true it up with a tire lathe.

Resin is quite heavy. (Polyurethane)

 

[King blitz]

I cut the hub out of a hoon I’m thinking about casting it in polyurethane just thinking about it

Try it .it's worth the shot

 

[Jerold]

Resin is quite heavy. (Polyurethane)

Another reason to keep them narrow.

 

[fozzy71]

Dude, Skate wheel style might be the way to go.

Resin is quite heavy. (Polyurethane)

Skateboard wheels have to support 200# dudes landing on them, RC cars don't require that much strength/material I would think.

 

[King blitz]

Dude, Skate wheel style might be the way to go.

Skateboard wheels have to support 200# dudes landing on them, RC cars don't require that much strength/material I would think.

I'ma buy me a pink set of roller skate wheels .with some led lights in them .epic

 

[Dan B.]

Skate wheels don’t sound like a bad possible solution. But I do disagree with most here on this topic regarding rim composition. I don’t believe there would be any downside whatsoever to running a perfectly balanced set of aluminum rims. Deformation would be a thing of the past, and the extra weight would not be nearly the issue that many fear, as I’m not talking about a solid spherical chunk of billet, I’m talking about a nicely CNC’d conventionally designed rim. On a dedicated RC speed-run car, unsprung weight really ceases to be an issue because you really don’t give two poops at that point how the car handles. The suspension is all but locked out to begin with, and you’ll not be running any road courses with them.
Excess weight in a dedicated speed runner is quite simply a non issue. There is no issue supplying far more power than necessary at this point.
After seeing Kevin’s video and being shocked by the deformation of the wheels, I immediately went back to thinking that with a rigid, non-deforming rim we could perhaps get back to Kevlar reinforced and belted rubber instead of foams. In that configuration the “tire” would simply be a very thin band of super tough rubber that would only need to be a couple mm’s thick.
They should also be much thinner, with a 20-25mm cross section?

 

[King blitz]

Skate wheels don’t sound like a bad possible solution. But I do disagree with most here on this topic regarding rim composition. I don’t believe there would be any downside whatsoever to running a perfectly balanced set of aluminum rims. Deformation would be a thing of the past, and the extra weight would not be nearly the issue that many fear, as I’m not talking about a solid spherical chunk of billet, I’m talking about a nicely CNC’d conventionally designed rim. On a dedicated RC speed-run car, unsprung weight really ceases to be an issue because you really don’t give two poops at that point how the car handles. The suspension is all but locked out to begin with, and you’ll not be running any road courses with them.
Excess weight in a dedicated speed runner is quite simply a non issue. There is no issue supplying far more power than necessary at this point.
After seeing Kevin’s video and being shocked by the deformation of the wheels, I immediately went back to thinking that with a rigid, non-deforming rim we could perhaps get back to Kevlar reinforced and belted rubber instead of foams. In that configuration the “tire” would simply be a very thin band of super tough rubber that would only need to be a couple mm’s thick.
They should also be much thinner, with a 20-25mm cross section?

I said it a while back aluminum rim rubber tire..rubber is faster than foam ,but foam holds better at higher speeds..rubber tires still need to be designed to handle 150 plus mph. I also think the entire tire should be glued to the rim ,not just the sides...the solution to this tire and rim issue isn't just a one solution deal.i believe it's all three aspects .1 Rim 2 Tires 3 Glueing .wounder if stitching the tire to the rim would support the middle along with glue beads on the sides...just thinking out side the box but what about a leather and rubber infused tire.. Mean while.i called my boyz down at Boston Bruins and they sending me some hockey pucks

 

[LibertyMKiii]

I said it a while back aluminum rim rubber tire..rubber is faster than foam ,but foam holds better at higher speeds..rubber tires still need to be designed to handle 150 plus mph. I also think the entire tire should be glued to the rim ,not just the sides...the solution to this tire and rim issue isn't just a one solution deal.i believe it's all three aspects .1 Rim 2 Tires 3 Glueing .wounder if stitching the tire to the rim would support the middle along with glue beads on the sides...

This is a good point. If GRP tires hold pretty well up to 140 with zero support in the middle having them glued 100% across should increase that speed reliability significantly higher. I wonder if it could be as simple as removing the tire and inserting a plastic spacer under the rubber tire that is glued in. You could throw in some kevlar belting or something to help control the expansion.

 

[King blitz]

This is a good point. If GRP tires hold pretty well up to 140 with zero support in the middle having them glued 100% across should increase that speed reliability significantly higher. I wonder if it could be as simple as removing the tire and inserting a plastic spacer under the rubber tire that is glued in. You could throw in some kevlar belting or something to help control the expansion.

Exactly.if you watch when a tire balloons, you allways see the middle expands upwards and the sides are on the rim glued right? Well eventually The sides give out due to the upward force.that ballooning is pulling the glued sides away from the rim .if the middle is reinforced then ballooning is prevented which should stop the blowing of these tires ..glue that whole fkin tire down .I also was thinking of taking like 4 thin strips of flat foam wrapping each layer around the rim glueing down each strip on top of each other so like a layered cake .then at the end feather off where the ends meet ,so instead of a solid tire now it's layers of foam but they all glued down to each other..would ballooning happen ? I doubt it
Do you guys reamember the old bikes we had.Roadmasters..reamember the rubber tires filled with cement? Heavy as fk right but none ever got flat ..ok so grabb a set of wheels take out the foam inserts and fill that rim with epoxy .or cement i bet it won't baloon or blow out. You might blow the motor first
.

 

[Dan B.]

Exactly.if you watch when a tire balloons, you allways see the middle expands upwards and the sides are on the rim glued right? Well eventually The sides give out due to the upward force.that ballooning is pulling the glued sides away from the rim .if the middle is reinforced then ballooning is prevented which should stop the blowing of these tires ..glue that whole fkin tire down .I also was thinking of taking like 4 thin strips of flat foam wrapping each layer around the rim glueing down each strip on top of each other so like a layered cake .then at the end feather off where the ends meet ,so instead of a solid tire now it's layers of foam but they all glued down to each other..would ballooning happen ? I doubt it

If the wheel itself continues to distort anywhere near what is shown in that video than no amount of glue, foam, Kevlar, or faerie dust will prevent failure. I think the solution is going to be in two parts, the rim itself and either a rubber or foam compound that can withstand those kinds of RPM’s.
I was shocked to see the amount of deflection in the rims. That’s totally what caused the failures. No tire of any sort could be expected to remain intact at that point.

 

[King blitz]

If the wheel itself continues to distort anywhere near what is shown in that video than no amount of glue, foam, Kevlar, or faerie dust will prevent failure. I think the solution is going to be in two parts, the rim itself and either a rubber or foam compound that can withstand those kinds of RPM’s.
I was shocked to see the amount of deflection in the rims. That’s totally what caused the failures. No tire of any sort could be expected to remain intact at that point.

Yup all 3 parts need to be thought of.and that's including the glueing part as well.cant be eliminated from the equation.which will be part of the solution.

 

[Tex Koder]

I'm looking to come up with a rough basic design for a high speed wheel dyno.

I have something in mind now that should be feasible to create in one's garage.. Hopefully.
(In a somewhat controlled environment)

Will try to incorporate > Speedometer (MPH) in realtime ,digital Tachometer to gauge the rim's RPM and Wind speed meter to monitor air velocity going around the wheel & suspension components...

 

[King blitz]

I'm looking to come up with a rough basic design for a high speed wheel dyno.

I have something in mind now that should be feasible to create in one's garage.. Hopefully.
(In a somewhat controlled environment)

Will try to incorporate > Speedometer (MPH) in realtime ,digital Tachometer to gauge the rim's RPM and Wind speed meter to monitor air velocity going around the wheel & suspension components...

What kind of fans will you use to replicate high velocity wind flow?