If I understand it correctly, an XL-rated tire has a higher load index, so let's say 94 instead of the more usual 91, for example.

My questions are:

1. Is the XL rating achieved by reinforcing the sidewalls? If so, is it safe to assume that the sidewalls are much stiffer compared to the non-XL rated version (assuming same speed rating)? And does that result it reduced comfort?

2. Is it safe to assume that an XL-rated version will be heavier? Noticeably heavier in street driving?

3. Would an XL-version be more resistant to bulging out (breaking cords) if one hit a pothole, for example?

4. Should an XL-rated tire be inflated less than a non-XL tire since presumably it'll reach its required load rating at a lower PSI level? How much less?

5. Is there any benefit to running an XL-rated 225/45/17 summer tire on a B5 A4?

6. Are there any cons of running an XL-rated tire on a B5 A4 (besides the increased weight)?


Sorry for all the questions. This suddenly sparked my interest as there is a number of tires that are offered in both standard and XL versions.

Thanks!

The only reason to buy an XL tire (other than price if one happens to be cheaper) should be if you have a car that requires it or you intend to keep the vehicle fully loaded much of the time.

1. Is the XL rating achieved by reinforcing the sidewalls? If so, is it safe to assume that the sidewalls are much stiffer compared to the non-XL rated version (assuming same speed rating)? And does that result it reduced comfort?

Usually done with extra reinforcement on the sidewall, sometimes the tire is slightly stiffer. As far as noticable stiffness, I'd say not always, more of a tire by tire basis. Normally if there is any noticable difference it is very minor.

2. Is it safe to assume that an XL-rated version will be heavier? Noticeably heavier in street driving?

Not a large difference, really depends on the tire. Not enought that I could tell a difference in driving. On the F1GSD3 in 225/45R17 it is 2.5lbs per tire.

3. Would an XL-version be more resistant to bulging out (breaking cords) if one hit a pothole, for example?

In theory they may be ,but we've not found XL tires to be any more resistant to pothole damage. These tires can be inflated to a higher air pressure, but were not designed to be any more impact-resistant.

4. Should an XL-rated tire be inflated less than a non-XL tire since presumably it'll reach its required load rating at a lower PSI level? How much less?

Definitely not meant to be inflated less. Its the air in the tires that carries the load of the vehicle. Less PSI= less load capacity of tires in the same size.

5. Is there any benefit to running an XL-rated 225/45/17 summer tire on a B5 A4?

Not that I can see on this car as the standard load 225/45R17 tires already have enough load capacity.


6. Are there any cons of running an XL-rated tire on a B5 A4 (besides the increased weight)?

No cons that I've ever felt when testing XL tires on any car versus their standard load counterparts besides possible increased weight. I realize in theory they should be slightly stiffer, but the difference was so small that it was not noticable to me.