Go Back   Physics Help Forum > College/University Physics Help > Advanced Mechanics

Advanced Mechanics Advanced Mechanics Physics Help Forum

LinkBack Thread Tools Display Modes
Old Apr 23rd 2017, 10:55 PM   #1
Junior Member
Join Date: Apr 2017
Posts: 1
Race Car vs. Truck Tire Wheels Rot. Dynamics

Using your knowledge of rotational dynamics and material properties,
explain why large, thick tires are used more often on heavy-load-bearing trucks (or mountain bikes)
whereas smaller wheel and thinner tires are better for sports cars (or road bikes). For concreteness,
you might compare a wheel with an 30 cm Al rim and 10 cm rubber tire to a wheel with 25 cm
Al rim and 4 cm tire. As an estimate, that you may improve upon with your own research, you
may use that the density of aluminum (a common choice for wheel rim) is ρAl ≃ 2.7 g/cm3 and
its Young’s modulus is YAl ≃ 70 GPa, whereas for generic rubber the density is ρ <∼ 1 g/cm3 and
Y <∼ 0.1 GPa. (For very large construction vehicles, the rubber is considerably reinforced, but this
does not change the reasoning.)
DANNY is offline   Reply With Quote
Old Apr 27th 2017, 02:35 PM   #2
Senior Member
Join Date: Aug 2010
Posts: 384
It should be fairly evident why wide tires are better for heavy trucks on the basis of pressure upon the road.
HallsofIvy is offline   Reply With Quote
Old Apr 27th 2017, 03:06 PM   #3
Physics Team
ChipB's Avatar
Join Date: Jun 2010
Location: Morristown, NJ USA
Posts: 2,326
The question is very poorly worded, but I believe its not about the width of the tire profile but rather about the height of the tire profile and/or the thickness of the rubber that makes up the tire. Obviously the thicker the rubber the greater the mass of the tire and hence the greater its moment of inertia. And same applies to wheels and tires that have larger diameters. So by this reasoning the smaller the diameter of the tire and the lighter the rubber the less torque is needed to get it to rotate faster, which is good for sports cars and lightweight bikes. But where heavy loads are concerned and you are less interested in acceleration the thicker rubber material helps reduce stresses in the tire and extends its useful life.
ChipB is offline   Reply With Quote

  Physics Help Forum > College/University Physics Help > Advanced Mechanics

car, dynamics, race, rot, rotational kinematics, tire, truck, wheels

Thread Tools
Display Modes

Similar Physics Forum Discussions
Thread Thread Starter Forum Replies Last Post
Rotational force on the points of wheels bsnayak Kinematics and Dynamics 2 Sep 15th 2015 10:57 AM
Tire Alignment (how to calculate tread wear) gvalch Kinematics and Dynamics 3 Jul 3rd 2012 06:38 AM
Locking of Wheels and ABS- deltaxray Kinematics and Dynamics 0 Mar 2nd 2010 02:17 AM
A Tire and a Compressed Air Tank Thyferra2680 Thermodynamics and Fluid Mechanics 0 Sep 13th 2009 07:25 AM
Rotating Tire Angular Acceleration chris2g69 Advanced Mechanics 1 Feb 18th 2009 07:59 PM

Facebook Twitter Google+ RSS Feed