Touring car tire size, is it time for a change?
#1
Touring car tire size, is it time for a change?
The current tire issues at the Worlds warm-up got me thinking about current TC tire sizes, their history and whether or not it makes sense to think about change to at least the width, and perhaps the aspect ratio as well. Current tires are on 24 mm rims, which equate to a 1:1 car equivalent of ~245 mm section tires. I would consider that far from economy car tires, but nowhere near what many GT race cars/DTM cars use. For reference, DTM uses 300/320 section front and rear, respectively. Current WTCC Super 2000 regs dictate a max of 250 mm, but I would argue the car performance of that series is more equivalent to a 21.5/17.5-powered TC (yes I know scale speeds are way different). Given the level of performance of today's electric touring cars, particularly modified outdoors, is it not worth looking at adopting wider tires to increase load capability (and likely, tire life) and realism too? The only widely available slicks I know of that fit this range are the HPI Vintage Slicks.
I would even pose the argument of having different tire regulations for modified vs. spec classes. The full-scale racing world scales tire size with increasing power and performance, so why shouldn't we?
Discuss away.
I would even pose the argument of having different tire regulations for modified vs. spec classes. The full-scale racing world scales tire size with increasing power and performance, so why shouldn't we?
Discuss away.
#3
No.
#5
No
#6
The air density relative to downforce is always an interesting topic. Yes, the amount of downforce, in absolute terms is quite small, but relative to the mass of the car is quite significant.
#7
Tech Champion
iTrader: (34)
Sure, but if you multiplied everything by 10 you would be getting pretty extreme numbers, i.e. 600+ mph. As it is, our R/C touring cars generate far higher lateral and longitudinal accelerations than their full-size counterparts, mostly due to the scale mass being much less and the CG much lower.
The air density relative to downforce is always an interesting topic. Yes, the amount of downforce, in absolute terms is quite small, but relative to the mass of the car is quite significant.
The air density relative to downforce is always an interesting topic. Yes, the amount of downforce, in absolute terms is quite small, but relative to the mass of the car is quite significant.
What is the scale speed of a 1:1 F1 car ?
#8
Tech Elite
iTrader: (37)
One would need to also scale down the air. The general thought is that the Reynolds number should be the same to get reasonable results.
Full-scale designers are constantly begging for larger and larger wind tunnels, simply because the larger scale models they can use give more accurate results.
Full-scale designers are constantly begging for larger and larger wind tunnels, simply because the larger scale models they can use give more accurate results.
#9
Downforce from GT cars is in the hundreds of pounds relative to their 2000+ lb weight. R/C touring cars need to only generate in the range of 0.5 - 1 lb of downforce to generate equivalent levels relative to their weight. The fact that we can 'feel' changes between bodies that are very similar in profile means that there is significant downforce. Those differences between race bodies are often the change in center of pressure, i.e. shifting where the majority of the downforce acts relative to the CG of the car, rather than a large change in total downforce.
Anyway, back on topic. For those who are saying "No", do you have a justification for your reasoning, or are you content to say no because it's simply something different?
#11
There is a couple of ways of thinking about it. I'm not a scientist or an engineer, nor will I pretend to be.
What is the difference in gains between PSI of contact area and friction/psi of the tire contact patch? I'm just going to pull numbers and they are totally unrealistic numbers so don't pick them apart. Lets say you have a 24mm, tire width that we have now and when it's on the car, ready to o on the start line it spreads out and gives 96 square mm of contact patch, but it creates 3 psi of weight on the tires.
Now you have a 28mm width tire, it will create 112 square mm of contact area. Now you've reduced the weight on the tires contact patch to maybe 2psi. Are the friction gains, assuming the same surface on both tires, going to make up for the lack of pressure on the tires? I know the cars will weigh the same and have the same wight pushing down on the tires but it comes down to surface area as well.
I hope this makes sense to people. If not I can try and explain it better.
Again, I am no engineer or scientist or anything. Hopefully someone will have better answers.
What is the difference in gains between PSI of contact area and friction/psi of the tire contact patch? I'm just going to pull numbers and they are totally unrealistic numbers so don't pick them apart. Lets say you have a 24mm, tire width that we have now and when it's on the car, ready to o on the start line it spreads out and gives 96 square mm of contact patch, but it creates 3 psi of weight on the tires.
Now you have a 28mm width tire, it will create 112 square mm of contact area. Now you've reduced the weight on the tires contact patch to maybe 2psi. Are the friction gains, assuming the same surface on both tires, going to make up for the lack of pressure on the tires? I know the cars will weigh the same and have the same wight pushing down on the tires but it comes down to surface area as well.
I hope this makes sense to people. If not I can try and explain it better.
Again, I am no engineer or scientist or anything. Hopefully someone will have better answers.
#12
Tech Regular
I'm not into league racing of RC cars, but I think this is something that definitely should be looked at, considered and even experimented with, at least on a trial-run basis.
How long have RC cars been using the 24mm wheel/tire? How many technological advancements have been made to RC car chassis and motor/esc since then?
Are the 24mm tires now being pushed beyond their limits?
If increasing tire size could increases competitiveness and continue progression, why not?
How long have RC cars been using the 24mm wheel/tire? How many technological advancements have been made to RC car chassis and motor/esc since then?
Are the 24mm tires now being pushed beyond their limits?
If increasing tire size could increases competitiveness and continue progression, why not?
#13
There is a couple of ways of thinking about it. I'm not a scientist or an engineer, nor will I pretend to be.
What is the difference in gains between PSI of contact area and friction/psi of the tire contact patch? I'm just going to pull numbers and they are totally unrealistic numbers so don't pick them apart. Lets say you have a 24mm, tire width that we have now and when it's on the car, ready to o on the start line it spreads out and gives 96 square mm of contact patch, but it creates 3 psi of weight on the tires.
Now you have a 28mm width tire, it will create 112 square mm of contact area. Now you've reduced the weight on the tires contact patch to maybe 2psi. Are the friction gains, assuming the same surface on both tires, going to make up for the lack of pressure on the tires? I know the cars will weigh the same and have the same wight pushing down on the tires but it comes down to surface area as well.
I hope this makes sense to people. If not I can try and explain it better.
Again, I am no engineer or scientist or anything. Hopefully someone will have better answers.
What is the difference in gains between PSI of contact area and friction/psi of the tire contact patch? I'm just going to pull numbers and they are totally unrealistic numbers so don't pick them apart. Lets say you have a 24mm, tire width that we have now and when it's on the car, ready to o on the start line it spreads out and gives 96 square mm of contact patch, but it creates 3 psi of weight on the tires.
Now you have a 28mm width tire, it will create 112 square mm of contact area. Now you've reduced the weight on the tires contact patch to maybe 2psi. Are the friction gains, assuming the same surface on both tires, going to make up for the lack of pressure on the tires? I know the cars will weigh the same and have the same wight pushing down on the tires but it comes down to surface area as well.
I hope this makes sense to people. If not I can try and explain it better.
Again, I am no engineer or scientist or anything. Hopefully someone will have better answers.
#14
Nope.
#15
Tech Elite
iTrader: (66)
It probably is time to change. We use to run 26mm back i the foam days. But with every manufacturer make 24mm plastics and rubber and massive numbers being made for controlled tire racing it isnt going to happen. The only way it really would, is if a major race like the nationals or worlds didnt have a control tire. And 1 or 2 manufacturers made a tire and wheel combo for that race and it won. And not only did it win, but cars of the same chassis, and on 24mm tires did poorly.