[kach22i]

Originally Posted by redpoint5

Used to be 15" wheels were huge, and most cars were running 13 or 14" What happened? My truck runs 17".

Good question, one I've thought of many possible reasons for but was never really sure.

Did a search and found this.

Size Matters – Why Large Rim Diameter Tires are Here to Stay
https://www.tirereview.com/large-rim-diameters-tires/

According to tire manufacturers, larger rim diameter popularity is due to the push toward SUVs and CUVs and the driving benefits that go along with them, such as stability, a shorter braking distance and size proliferation in the tire market. But, the prominent reason is how the larger rim looks on a vehicle.

“The growth in demand for larger vehicles along with the increased focus on vehicle design has ultimately led to the sharp increase in larger rim diameters over the past decade, “ says Sonny McDonald, national training manager for Toyo Tires.

https://mechanics.stackexchange.com/...over-the-years

This is very huge subject.

İn a simple way; wider tire does not necessarily means better contact, handling or braking. It all depends the weight, adjustment of suspension and tire pressure. Wider (from nominal size) the tire tend the brake or accelerate badly. It may just serve for better cornering (if sidewalls are low enough) and easy cooling off.

Wider the tire more mass to move for engine and that means bad fuel economy.

There will be no considerable increase at the contact area with bigger tire size but just the shape of the contact area tend to change. If tire is too wide the contact area will be elongated to the sides more than front and backwards. Because you will need less pressure with wider tires.

I suggest to read more on this subject because it is very interesting and also vital for all drivers.

Pros and Cons of Bigger Wheels in Car
https://carfromjapan.com/article/ind...wheels-in-car/

Do smaller diameter tires on cars give a more comfortable ride than larger diameter tires? If so, why did they make wagon wheels so large, if not to make the bumps less harsh?
https://www.quora.com/Do-smaller-dia...mps-less-harsh

Do bigger wheels mean better comfort
Post #28
https://www.team-bhp.com/forum/india...comfort-2.html

There are two aspects to consider

1. Outer Diameter. The larger the diameter, the less will it be affected by potholes. For example a 12" OD may go into a 14" pothole,while a 15" OD will not, thus jerking the vehicle less.

2. Sidewall height. The more sidewall height the more air there is to cushion the ride.

If you upsize the rim diameter while keeping the outer diameter of tyre the same, you reduce the sidewall height, thus less air cushioning. It helps by reducing the overall tyre weight thus giving better high speed, but you get a bumpier ride n brocken roads.