[FalconUSAF]

Please help me understand why "wider tires" provide more (not less) traction.
With wider tires, isn't there effectively less weight per square inch (on the pavement), so wouldn't that equate to less grip/traction?

[aerokubectl]

It's not just surface area that matters for traction. It's all about equal distribution at low and high thresholds.

The footprint is what you're looking for with as flat/wide of a shape as possible.

Wider isn't always better. You have to look at the internal tire structure and see how far the shoulder is up the apex and what the apex material is. If your shoulders are too stiff and the center breaker isn't that stiff, you'll actually get liftoff in the center(high disparity in pressure vectors).

[ZM2]

The force of the air in the tire that holds the car up remains the same regardless of contact patch size, e.g. 35psi is the same in a narrow or wide tire.

But, if you can apply a consistent 35psi of force across a larger contact patch (more square inches), you can apply more total force to the ground.

This assumes dry pavement, whereas wider tires tend to be slower in the wet bc of hydroplaning, but it depends on how much water there is and if your tires can evacuate the water quickly enough.

[FalconUSAF]

Good stuff! Thx!!

[aerokubectl]

Originally Posted by ZM2

The force of the air in the tire that holds the car up remains the same regardless of contact patch size, e.g. 35psi is the same in a narrow or wide tire.

But, if you can apply a consistent 35psi of force across a larger contact patch (more square inches), you can apply more total force to the ground.

This assumes dry pavement, whereas wider tires tend to be slower in the wet bc of hydroplaning, but it depends on how much water there is and if your tires can evacuate the water quickly enough.

sorry but that's 100% wrong.

You can actually achieve the same total square area with the same inflation, the shape goes from a squarer to a more rectangular shape with a wider tire.

In regards to hydroplaning, it depends on the water volume actually. Wet(non-rain) conditions will yield a better footprint which has great stopping/handling characteristics.

Big grooves are not ideal for wet unless you have massive amounts of water.

[M Fifty]

Originally Posted by FalconUSAF

Please help me understand why "wider tires" provide more (not less) traction.
With wider tires, isn't there effectively less weight per square inch (on the pavement), so wouldn't that equate to less grip/traction?

Snow tyres tend to be skinny. So...

[ZM2]

Originally Posted by spetsnazos

sorry but that's 100% wrong.

You can actually achieve the same total square area with the same inflation, the shape goes from a squarer to a more rectangular shape with a wider tire.

In regards to hydroplaning, it depends on the water volume actually. Wet(non-rain) conditions will yield a better footprint which has great stopping/handling characteristics.

Big grooves are not ideal for wet unless you have massive amounts of water.

Nothing either of us have said is incorrect. Both of us haven't made our points clear on which of the many variables are the most important in each traction situation, e.g., you said the same thing I did about the wet, but in a different way.

We'll let our boy Jason explain better than both of us:

And maybe our Australian friends can explain this guy?

[CosmosMpower]

Not in rain

[ZM2]

Good dry/wet tire width test vid:

[FalconUSAF]

Soooooo, after all that, can we surmise that our BMW engineers have provided the "best" tire sizes (front/rear) for our M2C. If not, why not.

[aerokubectl]

Originally Posted by FalconUSAF

Soooooo, after all that, can we surmise that our BMW engineers have provided the "best" tire sizes (front/rear) for our M2C. If not, why not.

On a totally unrelated note:

One thing to keep in mind is that the wider you go with tires, the worse RR you're going to have. I'm not sure how much of a factor RR was in this car because its hard to say but car manufacturers push for every single ounce of fuel economy they can get away with...even for cars like the M2.

Wider tires impact track width unless you just squeeze inward and then you'll have a hilarious track/wheelbase setup. When you do move the track in, you start to lose interior space/engine bay space(kinematics aside).

[aerokubectl]

If anyone actually wants to improve their understanding I strongly encourage you guys check out:

https://www.amazon.com/Fundamentals-.../dp/1560911999

This book isn't that great for tires but great "rules of thumb". Overall there's a lot good stuff here re: suspension kinematics.

If you want a free license(pretty sure these guys are doing free trials these days) and want to play around with a simulation model to see what the performance would look like, check out OptimumG:

http://www.optimumg.com/

Now this book is a beast, but its basically the bible before you get into models based solely on test data:

Tire and Vehicle Dynamics:

https://books.google.com/books/about...page&q&f=false