pjorg

Need to replace the tires on my A6. Stock size is 205/55/16. I've heard that a "plus 0" upgrade is to go with 225/50/16. Is there any advantage to this aside from appearance?

Appreciate all opinions on this one.

CraigB

larger contact patch for increased dry traction/handling

pjorg

Contact patch size remains the same, as it is a function of tire pressure and car weight. However, with a wider tire, the patch would be wider which should give better lateral stability.

Guess I sorta answered my own question, thanks

jprice@CPS

THe width will give you enhanced lateral traction and stability, and will offer better braking distances too.

The downsides would be more likely to hydroplane, and not as good in deep snow and slush.

CraigB

"with a wider tire, the patch would be wider" = larger contact patch

Audi Junkie

Wider is not better. Try 205/60-16 for a better ride and better price or 215/55-16, very good too.

pjorg

Seems this topic comes up about every 6 months or so.

For ease of calculation, assume a 3000lb car with 30psi in each tire. That gives you 100 square inches of contact patch. You can change the shape and distribution of that contact patch with different size tires or by changing the wieght distribution, but you can't make it bigger unless you add wieght to the car or lower the tire pressure.

CraigB

Wouldn't 25mm of additional width (over a 205) increase the contact patch? 225 should be close to an inch wider than a 205 in the same brand/model of tire.

pjorg

As I understand it, with a wider tire the contact patch will get wider (duh!) but also shorter, so the overall area remains the same.
That's why you would get increased lateral stability, but as noted, reduced traction and possibly more hydroplanning.
I live in California, so weather is not much of a consideration for me.

CraigB

When I say contact patch, I'm referring to only the amount of rubber on the road.