Wider Tire = More Grip, right??? Hmm...

[drakkie]

Originally Posted by fpv_gtho

In the rain though width means little in comparison to tread depth and design.

True. When up to speed, it clearly has less aquaplaning then some other cars. Stationary it is a fairly big problem, as i tend to drive swiftly.

[Quiggs]

Originally Posted by 2ndclasscitizen

235 =/= wide.

Wide.

[culver]

I suspect your professor was probably correct but not getting his point across. I recall a few times when I was in school where a prof would be answering a question. I knew what was being asked. I knew what the prof was saying. The question and answer weren't related.

You are correct that wider tires generally result in more grip but it’s not as simple as wider = better.

In a sense your prof is right as the shape of the contact patch is very important. In general if you have a wide or narrow tire if you put the same 30psi of air in the tire you will have the same contact patch surface area. The difference is the shape of the contact patches.

He is also right about cooling a race tire. They can over heat.

Where things get muddy is a wider tire can allow you to run a lower pressure tire. Now you can get more area. Now more area results in lower contact patch pressure. Now you can run a stickier rubber.

So basically what you are saying is true but he is actually adding some of the dots that get you from wider tires to more grip.

[Kultag]

Btw. why do they raise the wheels of trucks when they are not loaded? I always thought that it's to increase the pressure under the remaining wheels so they could have a better traction for braking. (In other words: because of the big difference between loaded and unloaded weight.) Am I right?

[Quiggs]

There's regulations on tonnage per axle.

[macoran]

Originally Posted by drakkie

My car proves very well in the rain, that narrow tires don't have much grip. Almost every traffic light the tires are squeaking no matter how slow you accelarate...

squeaking ?? they may need some grease !

[Clivey]

Originally Posted by Kultag

Btw. why do they raise the wheels of trucks when they are not loaded? I always thought that it's to increase the pressure under the remaining wheels so they could have a better traction for braking. (In other words: because of the big difference between loaded and unloaded weight.) Am I right?

If the truck's unladen, you require less tyre contact to distribute the weight of the vehicle correctly. The advantage of raising the wheels is that the truck then becomes more manoeuvrable because less tyres are "scrubbing" aling the road as it turns and you save tyre wear on the unloaded tyres. At least, that's how I understand it.

[RacingManiac]

Originally Posted by culver

I suspect your professor was probably correct but not getting his point across. I recall a few times when I was in school where a prof would be answering a question. I knew what was being asked. I knew what the prof was saying. The question and answer weren't related.

You are correct that wider tires generally result in more grip but it’s not as simple as wider = better.

In a sense your prof is right as the shape of the contact patch is very important. In general if you have a wide or narrow tire if you put the same 30psi of air in the tire you will have the same contact patch surface area. The difference is the shape of the contact patches.

He is also right about cooling a race tire. They can over heat.

Where things get muddy is a wider tire can allow you to run a lower pressure tire. Now you can get more area. Now more area results in lower contact patch pressure. Now you can run a stickier rubber.

So basically what you are saying is true but he is actually adding some of the dots that get you from wider tires to more grip.

Ditto...

Originally Posted by RacingManiac

Interesting concept was explained in "The Consultant" section of Racecar Engineering a while back about the merit of wider tire. The common misconception is that wider tire = bigger contact patch area. This is not necessarily true(on the face value), as wider tire just simply means that your contact patch will be shaped differently(at a given tire pressure, narrow tire has a longer contact patch, but narrower, while a wider one is the opposite). However, being a wider tire it gives you a higher tire spring rate, which allows you to run at a lower pressure to get your desired wheel rate, hence the end result of "larger contact patch". While the softer tire spring will generate more heat which may help the compound to operate at its desired temperature, and wider tire do give you more tire "cooling" because of the extra surface area. All this though can vary greatly between car, tire, construction and compound.