- #1 of 130
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Mazda5: Tires & Wheels
by pf_flyer HOST
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Oct 02, 2006 (7:11 am)
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Talk about your Mazda5 tire & wheel issues here.
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- #2 of 130
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snow driving
by petero1
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Nov 17, 2005 (10:21 pm)
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Got my car back, and have now been driving in very snowy conditions in Winnipeg, Canada. I bought the base version, which in Canada has 16 inch wheels, specifically because I felt the tires would be better in Winter. Other than the low ground clearance and spoiler, which scoops up snow from the road, the car handles surprisingly well in winter conditions. Has anyone put on snow tires, and if so, did they find significant improvements in winter handling?
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- #3 of 130
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Re: snow driving [petero1]
by ffun
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Nov 18, 2005 (7:44 am)
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Replying to: petero1 (Nov 17, 2005 10:21 pm)
Why do you think 16 inch wheels will be better in winter? I've noticed that a lot of people also believe this but I've never gotten a good explanation as to why. Some say that a narrower tire is better at digging through the snow. That doesn't make any sense as modern winter tires are designed for traction on the snow rather than digging through it. When it comes to ice the wider your wheels are the better. Spreading out the weight gives you more traction on ice (Ever try walking on ice with skate guards on?). The only reason I can see 16" wheels being better is price. If I'm wrong, please let me know why.
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- #4 of 130
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Re: snow driving [ffun]
by frank4cars
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Nov 18, 2005 (8:24 am)
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Replying to: ffun (Nov 18, 2005 7:44 am)
The way I've always understood it, narrower tires will concentrate the weight over a smaller area and dig down, providing better contact with the road surface. Wider tires would act like a snow shoe and spread your weight so you would ride on top. But this doesn't have a lot to do with choosing a 16-inch wheel over a 17-inch one, as the section width will be almost the same. What the 16-inch wheel would allow is better availability. The standard 17-inch tires are more of a summer tire with their short sidewall. I don't think there are a lot of low-profile snow tires out there. Most available snow tires will have a taller sidewall as the tread block is taller than an all-season or summer tire.
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- #5 of 130
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Re: snow driving [frank4cars]
by ffun
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Nov 18, 2005 (8:59 am)
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Replying to: frank4cars (Nov 18, 2005 8:24 am)
The only way you'll ever dig down with a winter tire is if you are spinning your wheels. This is never a good thing and usually gets you stuck. You'll never dig down to the road surface. You'll just polish the snow into a nice icy rut. Most winter tires are designed with sipes provide traction on ice. The wider the tire the more sipes you have.
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- #6 of 130
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Re: snow driving [ffun]
by frank4cars
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Nov 18, 2005 (9:47 am)
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Replying to: ffun (Nov 18, 2005 8:59 am)
Yeah but the siping only disperses wet material. Snow packs into the tread fairly quickly and creates a slick. I would think you'd still want to dig down because it would give you better traction. The concentrated weight will also probably create more heat and help to melt the snow beneath it better. And on ice, logic says narrower is better. Think of a skate blade versus a shoe. The skate cuts in because the weight is concentrated on a point and allows you to accelerate away fairly easily. A shoe will just slide around. Of course studs and chains would be best. Maybe we need some engineers to weigh in on this. 
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- #7 of 130
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Re: snow driving [ffun]
by bfyerxa
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Nov 18, 2005 (10:02 am)
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Replying to: ffun (Nov 18, 2005 8:59 am)
On pure ice or hard pack a wider tire with the sipes would be better because of the larger contact patch, but in loose conditions, i.e., snow, slush, even gravel, you want a narrower tire to cut through the junk to the better surface below. Wider tires are nasty in snow and especially slush as they will "float". Here is an interesting site from MOT (Canadian Govt) regarding ABS with some info about longer stopping distances in snow.
As for low profile, e.g., 17" rims vs. 15" rims, I have no idea if that makes a difference in performance. All I know is trying to get 17" snows for the Mazda5 would be difficult and expensive. We are picking our GT today and I am hoping the tires are sufficient for this winter - next winter I will put on 15" rims with snows.
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- #8 of 130
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Re: snow driving [frank4cars]
by ffun
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Nov 18, 2005 (11:03 am)
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Replying to: frank4cars (Nov 18, 2005 9:47 am)
Your skate to shoe analogy is terrible. A skate has sharpened metal edges which gives you grip laterally but not strait ahead. If you want to compare wide versus narrow try walking on ice in shoes and then in skates with rubber guards on the bottom. You will definitely have better traction in the shoes (I know this as I have tried it).
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- #9 of 130
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Re: snow driving [bfyerxa]
by ffun
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Nov 18, 2005 (11:49 am)
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Replying to: bfyerxa (Nov 18, 2005 10:02 am)
This issue has been really bugging me so I've done a little bit of research and come up with the following.
1. Going to a smaller wheel will mean cheaper rims, tires, and more selection so it is definitely a good choice.
2. Friction is calculated using a coefficient of friction between two materials and normal force. Surface are is not really a factor. Therefore the width of the tire has very little effect on friction force.
3. Everyone experiences different winter driving conditions. I live in Edmonton, Alberta where we have long cold winters. Most of the driving I do is on plowed streets and highways. What concerns me is ice and packed snow. In this case I don't thing the size of the tire will make make much difference. If you encounter a lot of fresh snow and slush then I would agree that a narrow tire can be better. If you are driving through 6" of snow, there will be less rolling resistance on narrow tires and they will therefore require less traction to move forward. Narrower tires are also better for slush since there usually firm footing underneath the slush that you want to get to and a narrow tire can carve through the slush easier.
In summary, down sizing definitely makes the most financial sense. As far as ice traction goes it makes very little difference what size your tires are. Narrow tires can be better because of decrease rolling resistance through snow and cutting through slush to get to pavement.
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- #10 of 130
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Re: snow driving [ffun]
by bfyerxa
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Nov 18, 2005 (1:36 pm)
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Replying to: ffun (Nov 18, 2005 11:49 am)
I agree in Alberta tire width is not a big issue. Here in Ottawa where we do get a lot of slushy junk, wide tires are a quick ticket to the nearest ditch. And cost is a big issue as well - a buddy of mine got one of the first Infiniti G35 coupes with the big Brembo brakes. He could not physically get smaller rims (had 18") because of the brakes hence had to pop for $1300 in snow tires!
As for tire size not affecting overall traction, that is wrong. The concept of the available force simply being a factor of the coefficient of friction times force on the contact area is so simplistic it only applies to grade 9 science. In general you want as much tire contact patch as you can "afford" as long as the surface is reasonable. Once the surface turns to junk like gravel, snow, mud, slush, etc. then you are now into a completely different ball game.
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