SUV Handling: Tires & Friction - Equations Included

[ronicencen]

SUVs are supposed to be unsafe because of inferior handling... the main issue is center of gravity, but do the wheels have anything to do with it as well?

Do their wheels make it harder or easier to brake and turn?

Equations VERY appreciated!

 

[Ranger Mike]

SUVs ..poor handling...compared to what ??
I for one would much rather be cross arming a mid size SUV than the cheap, lite weight mini compact that folds up like a cheap suitcase when it T-bones the tree..guard rail..etc..
in fact , a car salesman buddies of mine ( also semi good round track driver) successfully sold my wife a larger new Automobile by simply having a budd help him LIFT the back of the entry level economy car off the ground..no rear weight at all..them pregneat rollerskates are totally dangerous in my opinion..plus they push like a freight train when rounding any corner at half decent speeds...
but here are the facts..




http://www.thetruthaboutcars.com/iihs-and-nhtsa-agree-suvs-safer-than-cars/

cut and pasted from the above
You remember that debate, don’t you? Back before carbon dioxide was a planet killer, before hurricane Katrina sent the price of gas soaring, before the Iraq war got old, the anti-SUV crowd focused their attention on safety. They highlighted the “us vs. them” SUV vs. car death match, where the guy with the morally indefensible vehicle won the right to play again. Which was unfair but true. And still is.

Last Thursday, the Insurance Institute for Highway Safety (IIHS) released the results of a study examining death rates for drivers of 2001 to 2004 model year vehicles involved in crashes from 2002 through 2005. The results were rated by deaths per million vehicle years (DMVY).

The IIHS’ separated the vehicles into eight categories: cars, sports, luxury, specialty, station wagons, minivans, SUV’s and pickup trucks. The “deaths by body style” stats were conclusive. According to the report, large and mid-sized 4WD vehicles (47 and 59 DMVY) are safer than cars classified as mini (148), small (103), midsize (71), large (81) and very large (61).

The IIHS report also listed the vehicles with the highest and lowest driver death rates. Of the 16 “worst” vehicles rated, cars occupied 12 slots, while SUV’s garnered four places on the list (a 75 / 25 percent split). Of the 15 “best” vehicles, five cars (33 percent), seven SUV’s (47 percent) and three minivans (20 percent) made the grade.

That said, the IIHS study rated both small and very large SUV’s appreciably more deadly than mid-sized and large SUV’s. And there are as many ways to spin interpret the IIHS data as there are media outlets happy to avoid the logical, distinctly non-PC headline “SUV’s Safer than Cars.”

One more thing...the prob with all the roll overs in the SUVs a few years back was poor operator maintenance...the tires were not kept up to proper inflation specs...all tires bleed thru the side wall over time..and you should check the mmonthly in the winter..( one reason we use nitrogen to inflate on race car tires)

 

[astrokreng]

I would like to address the concerns raised about SUV handling and the role of tires and friction in this matter. Firstly, it is important to note that the term "unsafe" is relative and can vary based on different factors such as driving habits, road conditions, and vehicle design. While SUVs may have a higher center of gravity compared to other vehicles, this does not necessarily make them unsafe. In fact, many SUVs are designed with advanced stability control systems and other safety features to improve handling and overall safety.

That being said, the center of gravity does play a significant role in a vehicle's handling. The higher the center of gravity, the more prone a vehicle is to tipping over during sharp turns or emergency maneuvers. However, this is not the only factor that affects handling. The tires and their interaction with the road surface also play a crucial role.

The type of tires used on a vehicle, including their size, tread pattern, and inflation pressure, can greatly impact its handling. Tires with a larger contact patch and a wider tread tend to provide better grip and stability, while underinflated tires can decrease handling performance. Additionally, the coefficient of friction between the tires and the road surface is also important. A higher coefficient of friction means better grip and traction, which can improve handling and braking.

Now, let's address the equations that are often used to describe the relationship between tires and friction. The first equation is the friction force equation, which states that the force of friction between two surfaces is equal to the coefficient of friction multiplied by the normal force (F = μN). In the case of SUV handling, the normal force would be the weight of the vehicle acting on the tires. This equation shows that a higher coefficient of friction can result in a greater friction force, providing better grip and control.

The second equation is the force of rolling resistance equation, which states that the force required to keep a tire rolling is equal to the coefficient of rolling resistance multiplied by the normal force (F = CRRN). This equation highlights the importance of properly inflated tires, as underinflated tires can increase rolling resistance and make it harder to brake and turn.

In conclusion, while the center of gravity does play a role in SUV handling, it is not the only factor to consider. The type and condition of tires, as well as the coefficient of friction, also significantly impact a vehicle's handling performance. It is important for SUV owners to regularly check and