Duh, I missed the obvious. I really meant an indentically sized diameter
wheel, i.e a 13" or 14". However the example you site still makes the
point about contact patches.
Larry
(Who live in PA and misses the snow in Wyoming. where I love to drive in
the stuff all winter)
>>>>On 12/18/99 1:34 PM so and so (REwald9535@aol.com) said. (And I quote:)
>Can I toss in my $.02 here?
>Lets say you have a car that has 185/75/14 (just to pick a size) if you go
>to
>a 195/65/15 the tyre will have the same diameter. This is called plus one
>(One inch larger rim = shorter sidewall) If you then go to a 205/55/16 again
>same diameter. This is called plus two. Go up one more size to a 215/45/17
>plus three. Now I haven't been to the tire store today, but I will be
>willing to bet that at 215/45/17 is wider, and has a larger contact patch
>(square inches) than a 185/75/14, yet they will have the same outer
>diameter.
>
>This whole discussion reminds me of when I sold tires and a customer would
>come in and ask for a 15 inch tire. What size 15 tire I would ask, and they
>would reply it doesn't matter. So I would roll out a 165/15 VW tire and an
>L70/15 tire for a caddie. The look on their faces was worth it.
>Rick
>(Who lives in California where we have lots of snow, but we keep it in the
>mountains where we can visit it when we want to, we don't live in the stuff)
>(gonna be 75 today)
>
>In a message dated 12/18/99 7:04:00 AM Pacific Standard Time,
>macy@bblmail.psycha.upenn.edu writes:
>
>> - I have no idea where you grew up and learned to drive but anyone that
>> thinks that wider tires perform better in the snow is asking for trouble.
>> Look at any snow tire anywhere and what do you find - A narrow tire with
>> an aggressive tread pattern. I am not talking about a worthless
>> "All-Weather" tire. I mean a real snow tire. A wider tire decreases the
>> weight to surface area of the tire. So that for the same weight car a
>> narrow tire has more of the weight on the tread than a wider tire. (PS I
>> also disagree with the concept that a wide tire of the same diameter has
>> the same contact patch than a narrow tire). This information is based on
>> reading, and personal experience. Try taking a RWD car with the factory
>> tires out in the snow. Take the same car with a wide "sport" tire in the
>> same snow. Wanna see the ass end in front of you real fast??? BTDT Wide
>> tires do not hold in the snow. Wanna go out in the boonies in the winter
>> to go hunting?? You will never get there in one of those 4x4's with the
>> fat tires. Unless you are talking balloon tires and that is a whole
>> 'nutter concept of moving over the snow - not through it. Tread pattern
>> has more to do with the ability to move in the snow than any other idea.
>>
>> Larry
>>
>>
>> >>>>On 12/18/99 8:52 AM so and so (Allen Hefner) said. (And I quote:)
>>
>> >In a message dated 12/17/1999 5:41:36 PM Eastern Standard Time,
>> >mvheim@studiolimage.com writes:
>> >
>> ><< Simple. It doesn't. They have the same contact area, just different
>> > length & width dimensions. More width x less length = same area.
>> >
>> > Let me repeat: wider tires do not give you a bigger contact patch
>(unless
>> > you also lower the tire pressure). They just change its shape. It just
>> > happens that the shape makes a difference. >>
>> >
>> >- - - - - - - - - - - - - - - - - - -
>> >
>> >Keep in mind that what we are comparing is two tires that are EXACTLY the
>> >same. The same rubber compound, the same sidewall height, the same
>> sidewall
>> >stiffness, the same tread, AND the same tire pressure, all on the same
>car.
>>
>> >In that case, the contact patch will be the same area, even with
>different
>> >width tires.
>> >
>> >Back to the real world. Wider tires are of no advantage if they have the
>> >same sidewall height and stiffness. They aren't much stickier (for
>> >competition use, at least) if they don't have a softer rubber compound,
>> >etc.
>> >So in the real world, narrower, taller tires tend to have a smaller
>contact
>>
>> >patch area than wider, lower tires (that you probably bought to make the
>> car
>> >corner better in the dry), and so they are better in snow.
>> >
>> >Ok...back to LBCs.
Larry Macy
78 Midget
Keep your top down and your chin up.
Larry B. Macy, Ph.D.
macy@bblmail.psycha.upenn.edu
System Manager/Administrator
Neuropsychiatry Section
Department of Psychiatry
University of Pennsylvania
3400 Spruce St. - 10 Gates
Philadelphia, PA 19104
Ask a question and you're a fool for three minutes; do not ask a
question and you're a fool for the rest of your life.
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