I believe #2 is wrong. The more rubber you put to the ground, then the more traction you get.

 

2 is actually true. Its the shape of the contact patch that changes with a wider tire, not the size. Contact patch size is a function of vehicle weight and its distribution, sidewall stiffness, and air pressure.

Unsprung weight, yes, but with the wider tire, you can achieve more lateral grip, assuming identical tire comounds.

 

I believe #2 is wrong. The more rubber you put to the ground, then the more traction you get.

Its a common misconception that wider tires will give a larger contact area than narrower tires (for the same tire pressure) Contact area is only a function of tire pressure and weight of the car. A wider tire will have a wider and shorter contact patch than a narrower tire.

 

Okay so I googled this and came across a really good answer. I'll quote it below and then give the link to the whole thread:

GreenV8S (Peter Humphries):

"The school physics books tell you that the coefficient of friction is a constant, but in reality this is an oversimplification. In the case of tyres, the coefficient of friction drops off as you increase the weight on the wheel. This is why you can tune a car's handling by adjusting the anti-roll bar, and also why you *can't* tune with anti-roll bars if the load on the tyres is too small (the vehicle is overtyred).

Because of this, the bigger the contact patch the more grip you can get. In a drag race, dropping the tyre pressure increases the contact patch area and increases grip. Even on road bikes you will see people dropping the tyre pressure to almost nothing for the absolute maximum grip down the strip.

BUT, when you look at lateral grip (side force) other factors start to matter. The tyre develops side force because of the slip angle between the tyre and the road. This slip angle means the tread is being pulled sideways by the road surface. At the front of the contact patch the deflection is relatively small. As you move back along the contact patch the deflection increases steadily. At some point, the sideways forces in the tyre exceed the friction between the tread and the road and the tread starts to slip relative to the road. When the tread is slipping like this it produces less grip on the road. Now imagine increasing the slip angle and imagine what effect this has on the side force. As the slip angle increases the sideways deflection builds up quicker so the front of the contact patch works harder. But more and more of the back of the contact patch is sliding and losing grip. At some point you reach a maximum point where more slip angle means less side force because you are losing more grip at the rear of the contact patch that you are gaining at the front. This is often referred to as 'breaking away' where you ask the tyre for more grip and end up getting less.

The longer the contact patch is, the more gradually this break away occurs. If you shorten the contact patch, the break away occurs more abruptly but you get more absolute grip at the peak. This is because there is less variation in sideways distortion between the front and back of the contact patch, more of the contact patch reaches maximum grip and starts to slide at the same point. Having a shorter contact patch also means you get less self-aligning torque so there is less feedback through the steering about how close the tyres are to breaking away.

When you fit wider tyres, what you're doing is making the contact patch wider and shorter for the same tyre pressure. This means you get a more abrupt breakaway but more grip right on the limit. The disadvantage is more expensive tyres, more tramlining and steering kickback, more wind and rolling resistance and noise, less grip in slippery conditions, a more abrupt breakaway to catch out the unwary driver and less warning through the steering about how close the tyres are to breaking away.

This probably explains why manufacturers tend to put wide tyres on high performance cars and narrower ones on ordinary family saloons."

http://www.pistonheads.com/gassing/topic.asp?f=48&h=&t=78848

 

excellent discussion. I feel better about my 195/65R15's now that I know I have the exact same contact patch as if I had gone to 205.

 

I had always been curious why VW put a 195 on a 7 inch rim. Heard that a more verticle sidewall gave better handling, so I thought that must be why. Then in reading some european magazines found out they use the same width on wheels down to 6". Started to think that they do it to get a massive discount on getting one size for all.

The most recent tires i bought are 205s. Only have 100 miles, and they are a different brand so comparison is hard, but I like them so far. I need an all season and going wider would make them not as good for winter. I hope they will protect my wheels better too.

The best tires I have had were 195/60/15 Potenza 950s. The dealer accidentally put on the wrong size, but they performed better than the 195/65/15 Poetenzas I bought later. On a track day I used up the full tread, but didn't overdo it. So I think 195 is fine - which tire you choose is a bigger factor.

PS the two reasons I didn't stick with the 950s are - they weren't a good enough all season to handle winter and they only lasted 30,000 miles. My new pair are BF Goodrich Traction TAs - we'll see how they do this winter.

 

SNIP...

I need an all season and going wider would make them not as good for winter. I hope they will protect my wheels better too.

I think these are points most people miss about wider tires. Wider is better for lateral grip and handling on dry pavement, but when the snow starts to fly a narrow tire is the way to go. The taller sidewall does protect the rims from pothole damage, and the narrower and longer tire contact area gives lower rolling resistance through snow and increased fore-aft traction before tire grip is lost.

So, to answer the title question of this post... It depends what performance you are interested in. Wider tires do not perform better in all conditions.

 

You need wider wheels to go with wider tires.
Otherwise, you get about the same contact patch.
BETTER tires is usually good, WIDER tires is usually not.

 

Shorter sidewalls will allow for less sidewall flex, and that contributes to better handling as well.

 

Kinda long...

You need wider wheels to go with wider tires.
Otherwise, you get about the same contact patch.
BETTER tires is usually good, WIDER tires is usually not.

You could say that, for example, a 205/55-16 Goodyear Eagle F1 GS-D3 will handle better than a 225/45-17 cheap piece of crap.

And as the long quote alludes to, "feel," or how much the driver can make of the feedback the tire provides, makes a big difference in how much of the available handling can be used.

That said, most drivers can't tell what their rubber is doing. How many don't even know when something is underinflated.... I can feel a difference of 2 psi from side to side on the front in everyday driving. If a tire isn't communicative, I'm not likely to wander too far into the performance envelope. Esp. with a FWD car like ours where the same axle has to steer, brake, and accellerate.

That said, most any high quality tire is more than adequate for 99.9% of what most drivers are able to do when they encounter what they find on public roads.

I autoxed for years (not that I ever won anything ). Except for emergencies, I never drive any car more than 5/10 on public roads. I can control my car, but I can't control other people or what is likely to be on the road.

 

The US Passat has 65 sidewall tires because americans like the big boat ride. You really do not know what this car can do with proper sports suspension and set of good sports tires. It feels like two different cars (it's not a Ferrari, but it's close to 3 series Beemer with sports susp).
What he's talking about in that article is the fact that high sidewall tire will have more of the "feel" when you drive it on the edge because the contact patch is N/S oriented. However wider low sidewall tire made of soft compound with E/W contact patch orientation will go way beyond what would be considered the breaking point of the high sidewall tire. Of course there will be less feedback and more abrupt loss of traction but most people will never push the car to those limits in street driving. Then again, in an emergency situation you have lot more grip and lot better directional control with low sidewall tire so IMO the wider low sidewall tire wins hands down.

 

The US Passat has 65 sidewall tires because americans like the big boat ride. You really do not know what this car can do with proper sports suspension and set of good sports tires. It feels like two different cars (it's not a Ferrari, but it's close to 3 series Beemer with sports susp).
What he's talking about in that article is the fact that high sidewall tire will have more of the "feel" when you drive it on the edge because the contact patch is N/S oriented. However wider low sidewall tire made of soft compound with E/W contact patch orientation will go way beyond what would be considered the breaking point of the high sidewall tire. Of course there will be less feedback and more abrupt loss of traction but most people will never push the car to those limits in street driving. Then again, in an emergency situation you have lot more grip and lot better directional control with low sidewall tire so IMO the wider low sidewall tire wins hands down.

I and the guy in the the article are talking about wider tires with the same profile.