Winter

[2forme]

Originally Posted by DSPographer

Snow physics:
Well, saying the physics of light vs heavy cars being better in the snow is simple is- over simplifying. Heavy cars need proportionally more force to turn or accelerate. But, tire friction is proportional to downforce which (without a wing) is based on weight. So, the two first order effects cancel and either a light or heavy car can be better in slippery conditions depending on how it puts its weight on the road. Typically the car weight to tire width ratio will be greater for a big heavy SUV than for a sports car. This makes them worse for warm/dry cornering and better for snow/hydro-planing conditions. Fitting winter tires with narrower tread and big grooves can make a big difference for the light sports car though. As long as you have the right tires and know how to drive, I think you should be able to navigate normal roads in a BRZ given the car chassis clears the snow. Then driving safely depends on driving slowly and gently enough to stay in your lane and stop in time. That is where I think SUV drivers go wrong. Even though a four-wheel-drive car feels much more sure-footed starting up in snow, its real advantage in cornering is not that great. Now the acceleration needed to corner (V^2/R) is proportional to speed squared, so it only takes a small speed increase to wipe out any cornering advantage of the big SUV in snow. So, a false sense of security in the snow leads to the SUVs in the ditches.

Thank you, but jmary doesn't care about physics. I guess they don't apply to him.

The main problem is kinetic energy and the work required to stop/shift it. A heavier car will have more kinetic energy, and ultimately more friction, but they aren't linear. As such they will require more work to stop than a lighter car. The problem lies when all that breaks threshold of traction, which to say is easier with a heavy car, than a light one

[FRiSson]

Some people learn through experience and inference. Others rely on education, statistics, and experience. For 100,000 years we relied exclusively on the former. But progress, since the Greeks, has relied on the latter. The only exception is religion. So, if you attack someone for having only an experiential understanding, you are in a sense attacking their religion. Therefore, it is a fruitless effort to convince them otherwise.

[jmaryt]

Originally Posted by DSPographer

Snow physics:
Well, saying the physics of light vs heavy cars being better in the snow is simple is- over simplifying. Heavy cars need proportionally more force to turn or accelerate. But, tire friction is proportional to downforce which (without a wing) is based on weight. So, the two first order effects cancel and either a light or heavy car can be better in slippery conditions depending on how it puts its weight on the road. Typically the car weight to tire width ratio will be greater for a big heavy SUV than for a sports car. This makes SUVs worse for warm/dry cornering and better for snow/hydro-planing conditions. Fitting narrow winter tires with snow tread with deep grooves can make a big difference for the light sports car though. As long as you have the right tires and know how to drive, I think you should be able to navigate normal roads in a BRZ given the car chassis clears the snow. Then driving safely depends on driving slowly and gently enough to stay in your lane and stop in time. That is where I think SUV drivers go wrong. Even though a four-wheel-drive car feels much more sure-footed starting up in snow, its real advantage in cornering is not that great. Now the acceleration needed to corner (V^2/R) is proportional to speed squared, so it only takes a small speed increase to wipe out any cornering advantage of the big SUV in snow. So, a false sense of security in the snow leads to the SUVs in the ditches.

in a blinding snow storm,i would much rather have a heavier vehicle (s.u.v.-truck with weight in the box) under my ass than try to make headway in a "light" sports car! IF you drive "intelligently" ie: "slow" for the existing conditions,you shouldn't encounter difficulty turning,OR stopping! a person doesn't require a degree in physics to figure this out! i'll take my chances,(and be better served) in the heavier vehicle every time!. my "real life"
experiences driving under slippery,limited traction conditions have,without the slightest doubt, favored the "heavier" vehicle.

[Turbowned]

Lighter cars have less mass to get moving, less mass to rotate, and less mass to slow down. The silica compound in snow tires makes up for the lack of weight to get the traction that's needed. A heavier vehicle is only safer once you've hit something, and even that is arguable given the FR-S/BRZ's "Top Safety Pick" given by the IIHS.

Here's an interesting bit about snow tires, written by Alex Mouroulis on tirerack.com:

"Modern winter / snow tires utilize soft compounds that bring high levels of snow and ice traction. This level of grip is offered by having three very important characteristics. The first factor is tread depth. The best snow traction comes from a tall, deep tread pattern that will pack snow in, causing snow on snow contact, and therefore, providing excellent traction. When there's less deep tread depth, the tire is less likely to hold snow. This is why tires designed for muddy conditions don't do as well in snow.

The second factor is tread pattern. A big functional feature is the amount of siping a tire has, as sipes are engineered slits in the tire's tread pattern that come open as the tire rolls over the snow, creating more biting edges. Certain retailers offer a service to cut your tires for more all-season traction, however this service hurts the way the tire handles and also imposes uneven treadwear. Tires are extensively engineered, why would you want to cut up the only connection you have with the pavement?

The final factor is tread compound. And while there is diversity among some of the manufacturers on this topic, one common point is a compound that remains flexible at low temperatures. Michelin and General both utilize a high silica compound that improves traction in wet and slushy conditions, while Bridgestone goes one step further with Tube Multicell technology. Tube Multicell is a compound with many long tube-shaped voids in the tread compound that gives the water somewhere to go as the vehicle passes over snow and ice. Bite particles are also a feature in many tires and on a very small scale, bite particles act like little tiny studs and offer more biting edges for snow grip."

http://blog.tirerack.com/blog/alexs-...now-tires-work

That being said, I'm still not planning on driving my BRZ in the snow next year. Not because I don't think it's capable, but because I don't want the salt and slush touching it. Now I just have to decide which car goes in the garage and which one stays outside, and what kind of winter beater I want...

[Tt3Sheppard]

Wish i could say the same but my FRS will be driven this winter. Cost of a winter beater + insurance and reg is much higher than 4 snow tires. I picked up a set of 4 Sport Edition Rims and Blizzacks for $350 on craigslist. Tires are 225/45/17 though so we shall see how they handle.

[jstn]

My plans involve the bus and taking advantage of the fact that I don't ever have to leave town or drive faster than 30 if I don't want to. Probably going to cheap out and not bother with winter tires since I don't ever have to drive more than 1.5 miles if I don't feel like it.

[DSPographer]

Originally Posted by 2forme

Thank you, but jmary doesn't care about physics. I guess they don't apply to him.

The main problem is kinetic energy and the work required to stop/shift it. A heavier car will have more kinetic energy, and ultimately more friction, but they aren't linear. As such they will require more work to stop than a lighter car. The problem lies when all that breaks threshold of traction, which to say is easier with a heavy car, than a light one

Kinetic energy is linear in mass but like centripetal acceleration it is proportional to the square of the speed (1/2) (M) V^2 = kinetic energy. To a first order approximation without aerodynamic effects, friction is also proportional to weight. So again I say the two effects of vehicle weight tend to cancel. The determining factor is then which car has tires that put the weight down in a way that achieves the most traction per pound. I think jmary didn't notice that I said that heavy SUVs often do have a small advantage over a light sports car in maneuvering in the snow. But, speed and tires matter much more. So as long as the snow isn't so deep the chassis scrapes, safe driving in winter really depends mostly on choosing the right tires and driving correctly.

As far as not being able to make headway at all in a light vehicle, I wonder what experience jmary has. My first car was a 2-door Ford Maverick which was as light as a BRZ except more heavily biased to the front with a heavy iron straight six. Even with an open differential I managed to drive in snowy conditions most anywhere even though I could only afford a single set of bias ply regular tires. I did see some people in big heavy cars sliding backwards on the same hills I was climbing though, so driver skill does matter too. My dad's cars that I borrowed back in the late seventies were a 1976 chevette with less than 1-ton curb weight and a big V-8 Ford LTD. The LTD had the best tires so it was a little better in the snow but I could climb hills in any of these cars. The LTD was the trickiest to stop because the feather-touch power brakes had *zero* feedback with only the pedal spring resistance being felt right to fully locking up the tires in any conditions.

[jmaryt]

Originally Posted by jstn

My plans involve the bus and taking advantage of the fact that I don't ever have to leave town or drive faster than 30 if I don't want to. Probably going to cheap out and not bother with winter tires since I don't ever have to drive more than 1.5 miles if I don't feel like it.

Originally Posted by Turbowned

Lighter cars have less mass to get moving, less mass to rotate, and less mass to slow down. The silica compound in snow tires makes up for the lack of weight to get the traction that's needed. A heavier vehicle is only safer once you've hit something, and even that is arguable given the FR-S/BRZ's "Top Safety Pick" given by the IIHS.

Here's an interesting bit about snow tires, written by Alex Mouroulis on tirerack.com:

"Modern winter / snow tires utilize soft compounds that bring high levels of snow and ice traction. This level of grip is offered by having three very important characteristics. The first factor is tread depth. The best snow traction comes from a tall, deep tread pattern that will pack snow in, causing snow on snow contact, and therefore, providing excellent traction. When there's less deep tread depth, the tire is less likely to hold snow. This is why tires designed for muddy conditions don't do as well in snow.

The second factor is tread pattern. A big functional feature is the amount of siping a tire has, as sipes are engineered slits in the tire's tread pattern that come open as the tire rolls over the snow, creating more biting edges. Certain retailers offer a service to cut your tires for more all-season traction, however this service hurts the way the tire handles and also imposes uneven treadwear. Tires are extensively engineered, why would you want to cut up the only connection you have with the pavement?

The final factor is tread compound. And while there is diversity among some of the manufacturers on this topic, one common point is a compound that remains flexible at low temperatures. Michelin and General both utilize a high silica compound that improves traction in wet and slushy conditions, while Bridgestone goes one step further with Tube Multicell technology. Tube Multicell is a compound with many long tube-shaped voids in the tread compound that gives the water somewhere to go as the vehicle passes over snow and ice. Bite particles are also a feature in many tires and on a very small scale, bite particles act like little tiny studs and offer more biting edges for snow grip."

http://blog.tirerack.com/blog/alexs-...now-tires-work

That being said, I'm still not planning on driving my BRZ in the snow next year. Not because I don't think it's capable, but because I don't want the salt and slush touching it. Now I just have to decide which car goes in the garage and which one stays outside, and what kind of winter beater I want...

washing it once a week with ''touchless" especially underneath,and you will be fine!

sorry not buying into the lighter the better! granted snow tires will allow for better traction,BUT you still need ''weight" ie: ballast to maintain forward momentum in extremely slippery conditions. the key to drive effectively in low traction conditions is to slow down,traveling faster than conditions will tolerate is a recipe for disaster,no matter WHAT you are driving!

Originally Posted by Tt3Sheppard

Wish i could say the same but my FRS will be driven this winter. Cost of a winter beater + insurance and reg is much higher than 4 snow tires. I picked up a set of 4 Sport Edition Rims and Blizzacks for $350 on craigslist. Tires are 225/45/17 though so we shall see how they handle.

i share your concern! mine will be shod with "all-seasons" but trust me,i will NOT be out in anything other than light snow conditions,and ONLY if i get "caught" on the road.plan to get off the road when the big ones come! even with that,in my view,trying to turn THIS car into a "snowmobile" is an exercise in futility.

[Tt3Sheppard]

Any of you guys slapping on snows for the next few days? Might be some snow around us.

[2forme]

Originally Posted by Tt3Sheppard

Any of you guys slapping on snows for the next few days? Might be some snow around us.

Nah I caved and bought a nice, light, winter beater. Was pretty cheap and will keep the BRZ out of the salt.

[Tt3Sheppard]

Originally Posted by 2forme

Nah I caved and bought a nice, light, winter beater. Was pretty cheap and will keep the BRZ out of the salt.

Probably the way to go. I was offered by my dad to have my 98 escort zx2 back for the winter but between needing tires for that car, reg, extra insurance it wasn't even worth it. plus I have no garage to store the FR-S

[jmaryt]

Originally Posted by 2forme

Not quite, I'm the type who will probably get a nice little winter beater and laugh at the people with big heavy cars who end up off the road.

But hey, screw physics and how the world actually works right? Just make sure you tell everyone what kind of car you're driving this winter so we can stay away from you.

you prove my point! the car will be "horseshit" in the snow because it's too light! do you really know what you are saying? if people slow down in a heavy car,they should never find themselves off the road! even light cars,(horrible as they may be in the snow) can navigate the light stuff with proper winter tires. at least well enough to get off the road so the plows can do their thing! fuck physics! i'll take the "heavier" vehicle every time if caught in a snow storm!
you sound like a f**in' lawyer running for political office! ehe! he! he!

[jmaryt]

Originally Posted by 2forme

Not quite, I'm the type who will probably get a nice little winter beater and laugh at the people with big heavy cars who end up off the road.

But hey, screw physics and how the world actually works right? Just make sure you tell everyone what kind of car you're driving this winter so we can stay away from you.

Originally Posted by 2forme

Nah I caved and bought a nice, light, winter beater. Was pretty cheap and will keep the BRZ out of the salt.

ehe! he! he! cheaper than a ($5.00) car wash?! it's all ya need to do! guess ya got money to piss away!.to each his own! just sayin'

[jmaryt]

Originally Posted by Tt3Sheppard

Probably the way to go. I was offered by my dad to have my 98 escort zx2 back for the winter but between needing tires for that car, reg, extra insurance it wasn't even worth it. plus I have no garage to store the FR-S

i plan to run mine,just be kewl,and take it slow,get off the road as soon as ya can,and you'll be fine!