Finding the right Tires

  • Thread starter blumist
  • Start date

Whats better? Front wheel or Rear wheel drive?


  • Total voters
    5
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  • #1
19
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Hi,
I am currently working on a project of building a fuel efficient car. My car has a carbon-fiber chassis, a glass-fiber mainframe and weighs about 110 k.g.s(with driver). I need to find some light weight tires that would go just about right with the rest of the design and also be able to control the overall rolling friction.
Also, i wanted to know if placing the engine in the rear of the car improves the efficiency or not.
Thankyou
 

Answers and Replies

  • #2
brewnog
Science Advisor
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Engine positioning won't directly matter. However, other related considerations will. Aerodynamics will play an important role, so if there's a 'bulge' where the engine is located, or vents required for cooling/aspiration then you'll need to think about that.

Tyres will depend on loads of things; what kind of car is this? A tiny, low speed, lightweight tarmac vehicle might get away with using bicycle tyres, anything faster will need something more specialised.
 
  • #3
19
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its a small car actually... a single driver would hardly fit in. Its about 2 meters in length and 110 cm high. What i need to do is increase its efficiency to as high as possible. Would bicycle tires do good? Anything else that i need to be taking into consideration? Thanks for the help.
 
  • #4
brewnog
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Well as I said, if it's not going to be doing high speeds, bicycle tyres would do a very good job. Think about it; road bike users are after pretty much exactly the same thing you are (minimum rolling resistance). One thing to consider if you go down that route is cornering; the way bikes and cars corner (and the associated loads on wheels and tyres) are fundamentally different. Give it some thought.

However, if you're going to be doing higher speeds, or have some other requirements (perhaps traction for acceleration/cornering/braking), grip, wet weather or non-tarmac performance, then you might need something else. You haven't really defined your requirements.
 
  • #5
19
0
Ok here goes,

I am planning to build a car worthy enough of participating in the Shell Eco marathon 2011. Now i have the design and power needs sorted out at the moment but there is still a lot i have to do here. Here is the basic goal that me and my team are working on.
"To build a car that can provide maximum attainable fuel efficiency"

Now we have chosen a chassis design that combined with the engine and the body weighs less than 60 k.g. The car is only 110 cms high and about 50 cm in width so air traction is almost controlled thanks to an aerodynamic design.

We are facing problems in choosing the right tires that would provide minimum friction. Our car wont do speeds above 30 kph and there are no tight corners or off-road patches on the track so its basically a 25 kph constant smooth drive on a race track. Our chassis design includes 3 tires to be places. 2 on the back, and one on the front. Now the braking system has to be strong enough to hold the car static while placed on a 30* slope. These are pretty much all of my requirements.
 
  • #6
brewnog
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I'd go with carbon fibre racing bike wheels and lightweight racing tyres, and be sure to get the cornering loads right (bikes don't corner like cars). With the extra weight you will need to consider tyre pressures.
 
  • #7
Another likely option if you wanted slightly higher speeds would be the motorcycle wheels with spokes. They are much lighter than car wheels and perform nicely for light weight vehicles. This is only if you want to attain higher speeds. For low speeds, the cycle tires should do fine.
 
  • #8
19
0
I'd go with carbon fibre racing bike wheels and lightweight racing tyres, and be sure to get the cornering loads right (bikes don't corner like cars). With the extra weight you will need to consider tyre pressures.
thanks for the info. Do you have any tires in mind that would do good?

I need to get the exact tire rolling drag co-efficient. Please point me to a link on the web that would serve my purpose. Thanks again!
 
  • #9
brewnog
Science Advisor
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No, it's your project, I'll leave it with you here....
 
  • #10
563
2
Search "bike rolling resistance".

You can test how much side load capacity a particular set of tires/wheels has by pulling sideways on the car. I think you'll find that regular bike wheels will withstand the cornering loads that you can expect but if your testing indicates the need, use wider hubs.
 

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