qaz393

those are definately replica.

do not listen to going downsizing the width of winter tires. there is not proof that narrow is better. stick to what you can afford and what is recommended by the manual. i would choose the 16" (even on a c350) due to more potholes during winter time to avoid repair times and costs to wheels.

the brakes on usa C300 are the same as canadian C250-V6. The canadian C300 has upgraded brakes which are the same as C350. (fronts only) I have seen many C300 use 16" rims.

Sportstick

Actually, there is. If you recall your physics class, the mass of the vehicle is a constant, and exerts a downward force through the tire contact patch. If the contact patch is narrower/smaller, the pounds per square inch of downward force increases, as the same mass results in the force being more concentrated. Increased downward force results in superior traction. Of course, the wheel and tire must fit the vehicle.

qaz393

have you found any test on tire width vs contact patch??? you will be suprised at the results..... tire pressure, wheel width and weight has more to do with contact area then tread width. tread width should be left to manufacture specs because of load capability and head dissipation.

higher pressure does not mean increased downward force....... the net force will remain a constant. also, you logic is flawed here. if you reduced contact area, you do not increase grip. why do road racer run wider tires?

read this. it tells you about contact area and causes.

http://www.performancesimulations.co...on-tires-1.htm

Sportstick

The net force is a constant as the mass exerting it is also constant. That is not the point...the pounds per square inch is. If that force is distributed over a larger contact patch, the force measured in psi is less at any given point, which is addressed in the following quoted sources when the tire is described as floating over the snow. The reason they point out the narrower tire cuts into the snow better is not simply because it is narrow, but because by being narrow, the downward force is greater by being less distributed.Try this.....stand on two feet and feel your comfort. Then stand on one foot, and feel the increased force on that one foot. It's the same for tires in snow.

Here is how Motor Trend summarizes it:

Myth: Wide tires provide better traction under all weather conditions. In fact, putting oversize snow tires on a car delivers better snow traction.
Fact: The opposite is actually true. Wide tires tend to "float" on deep snow, and the tread lugs never have a chance to "dig" through to the road surface to gain traction. Narrow tires are a better option in deep snow. The tire acts similarly to a knife cutting through butter; the blade works best when using the narrow edge to push through the butter rather than the wide flat side of the blade.

Read more: http://www.motortrend.com/womt/112_9...#ixzz1brGTZHnU


Here is how cars.com summarizes it:

One thing you won't see are winter tires that are significantly wider than the summer- or all-season models they replace. Intuition tells us that a wider tire gives better traction in snow, but in this case intuition is wrong. In most conditions, a narrower tire will dig down into snow and gain traction, where a wider tire is more likely to ride up onto the snow like a toboggan. Look to any racecar to see that intuition is back in force in the case of dry roads: When cornering on a track, wider is definitely better.

qaz393

most peopel make assumption. there is no real test just based off narrow vs wide in loose or packed snow. most people think narrower is better from seeing rally race car. however, they are runnning studded tires and need to clear off the snow and find ice where the studs can give them max grip.

in races without ice (snow + pavement), they run wider tires. since most people would drive these condition, wider is better. stick to manual recommended specs. the following video shows you wide tires in snow.

http://www.youtube.com/watch?v=cI6tmDEpwGU

Sportstick

Best wishes to you for a safe winter.

kevink2

The contact area is somewhat constant, as you suggested, but is also influenced by pressure and the stiffness of the sidewall. One Z rated track tire on my 7 went down to ~15 psi, while the others were at 32 psi. The tire was transferring load mostly through the sidewalls as vertical compression. And it looked just like the others, with a similar outer border of the contact patch. Another member experienced the exact same thing.

I have experienced going from wide A.S. tires to narrows (on another car), and it was a huge improvement in winter snow traction, as well as comfort.

With 205-55-16 vs 225-45-17, you have a much narrower contact patch for 2 reasons; the narrower tire width, and the narrower tread associated with a 55 series vs a 45 series. You may recall the old 78 series tire that had 50% tread width !

The narrower contact width tire has to crunch down less snow, and is able to use less power to progress, with less chance of spinning. The narrow tread width also compacts the snow more for better grip. With wide tires, the dynamic tendency is to ride on top of deeper snow.

Wide is good for the beach sand, bad for snow.


tread width should be left to manufacture specs because of load capability and head dissipation.

Racer's optimal tire width is based largely on hp. I recall a test of a VW Scirroco (great car) at a 2 mile road course. Same type/brand/dia tires were used with different widths (and contact widths). The second smallist was fastest. The big wide tires were slightly faster in corners, but the hysteresis and friction based heat losses resulted in less speed on the straights, slower lap times.

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kevink2

WRC races are amazing, drivers & co-drivers have the largest pair of spheres of any race car competition.

The do occasionally race on mixed conditions, tarmac and snow, and the choice is narrow.

btw, what makes you different than most people?

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qaz393

how does the side wall profile effect contact patch width in the first place???

liike what i said, there is no specific winter testing on this topic. most snow that i see are either packed or wet pavement which makes wider tires have bigger advantage. wider tires are better. in loose snow, most drivers will probably not know or feel the difference....

qaz393

you have to consider that the larger tires will have more weight requiring more energy to spin them.

big semi truck run 305. this helps with load and heat dissipation

qaz393

in tarmac and snow, they run wide tires if they are not allowed to run studded tires. look at the video above.

i consider myself different because i look at both advantage and disadvantage of wider vs narrow.

i personally run 205/60R16 for winter mounted on 7.5 inch wide rims. (most rims are 7 inch)

This is slightly larger than recommended by manual, but it was cost effective.

kevink2

Study the MFG data at Tirerack, and look at tires at a tire shop. Look at two steps, like 45 vs 55 series.

For those conditions, tire compound, siping, and ability to move water would be most important.

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kevink2

Excellent video. Sebastion Loeb is arguably the best dirver in the world. But, no snow was on the course. Think before you type. This tire is what would be considered in F1 racing as "intermediate" full width tires, for traction on the mostly wet roads, with some dry patches, and no snow.

Web based pontificator, sorry the shoe fits.

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kevink2

It was considered.

The weight difference between the fastest and the widest tire/wheel was only ~10 lbs. Based on a physics based analysis by myself, consistent with other engineers' analysies, the equivelant total static wheel weight, including the mass moment of inertia effects, is 1.7 times the scale weight.

Thus the total added weight penalty due to the heavier, wider tire/wheel is:

4 x 1.7 x 10lbs = 68 lbs. total for (4).

68/2500 x 100 = 2.7%

Given that the car was faster in corners with the widest tires, the 2.7% total accelerated weight penalty was small compared to the lap time difference.

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qaz393

back from the dead. if you guys think its good to run narrow tires, you can be like WRC people and run 145/80R16 on the mercedes. its the correct size. 16" has been proven to clear the C350 brakes, so i dont see why you narrow tire supporters are not doing this.

http://www.dmacktyres.com/?page_id=165

kevink2

1) it's not WRC people, it's WRC RACERS, using RACE tires. Ask them (those that live in far north) if they used the tires in your link on their street cars.

2) It's not been proven that those 16" rims would fit a W204.

3) You've been shown to be wrong with almost all your tire statements.

4) Again, a Web based pontificator. Please bug another forum where you can snow people.

As Sportstick said, Have a nice winter.

done

RLE

Here's some fat tires for qaz. All ready for snow on his street.

http://www.porsche.com/international...9c9bc7&lang=en

qaz393

16" rims do fit as gatekeeper has mention on his C350-4matic. Wrong?? im always correct.

GateKeeper

Yes it has been proven - 16" rims do fit and can be used, and I had no issues with the setup I used for winter

You have yourself a nice winter as well

qaz393

+1, i have seen many canadian spec C300 (uses the same front brakes as USA/Canada C350) with 16".

your ignorance make me LOL

kevink2

Gatekeeper: Yes it has been proven - 16" rims do fit and can be used, and I had no issues with the setup I used for winter

That be ONE data point, far from proof for all W204's. The 16" wheel I measured only had about .2" clearance to front caliper.

I am a believer in using 16" wheels on the C-Class cars, for best winter tire use, and for those that value comfort much more than performance. It also can be used as a single "full-speed" spare.

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Glyn M Ruck

Regarding tyres: It's all an issue of weight over contact patch for a given compound & design in defined conditions. 'Nuff said.

qaz393

do you know the dynamics of tires???? if you put a narrower tire on a car, the contact patch will become longer and narrower at the same time. this can result in almost identical surface area......

Glyn M Ruck

I understand tyres implicitly thanks to Michelin being sponsor of my race teams over many years - both bike & car. We have had complaints about you on this thread. Anymore nonsense & your activities on this board will be curtailed. You have been warned.

LandSeaAir

I really hope they bring the 2012 C350 4matic to the US.