It seems to me that with every new model of a car, tires are getting bigger. For example, 17 years ago I had Mitsubishi Mirage and it came with P155/80R13. Today I have a Hyundai Accent, and it came with P175/70R14.
What is the purpose of a bigger tire? Why do newer cars come with bigger tires? Is it related to the increasing weight of cars? Is it for stability, fuel economy, or comfort?
Well, your basic premise isn't actually correct. There are a lot of cars which take a 14 and a lot of tyres which are as narrow as your old ones.
That said, tyre technology has moved on so it is now easier and cheaper to make wide tyres which are structurally able to cope, and in most conditions more rubber touching the ground means more grip (let's exclude deep water or snow where a narrower tyre can get more grip)
A greater footprint actually impacts fuel economy quite badly, as you get more friction with a wider tyre.
We have touched on low profile tyres previously, and the added control they can bring, but that isn't really relevant for this question.
Part of the reason for the larger tires is style,people like the look of the larger wheels. The second is handling,even small cars can now produce more horsepower than some full size cars of yesteryear. The shorter aspect ratio or tire sidewall height reduces tire squirm or the tendency of the tire to roll in turns. The wider tire also brakes better. This results in more predictive and consistant cornering and less torque steer. Torque steer is the tendency for front wheel drive vehicles to pull to the side under acceleration. I am sure some of the reasons are also lawsuit related. If you make a car that can go 100+ mph it better handle well at 100+mph.
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.
One reason is that cars are heavier than they used to be due mostly to safety and emissions requirements. My 2003 Mini (not all that new) a car weighs 2800ish pounds replaced a 2200ish pound 1985 Civic that was pretty similar in size (the Civic actually had slightly more interior room). Heavier cars need bigger tires.
Actually, it's kind of swinging the other way now, at least partially... While the OEM diameter keeps getting larger (for better & more responsive ride/handling), they're going back to skinnier tires on new cars for better fuel economy. To the point where I have a hard time finding tires that fit my older cars properly. For example, I need 245/45R16 and everything today seems to be 225 and narrower (except for some extreme examples).
I believe it's simply to keep up with trends . They see what's being done with cars by the generations that have passed. Each year new AFTER MARKET parts become new hot accessory, like TV's, chrome molding, & bigger rims. Gotta stay current, target the younger or more adventurous souls. Why should they allow you to spend more money with someone else when they can can get it all the first day you pull off?
Small and light cars like the Mazda 3 and Civic are standard with 205-55r/16. these tires are quite wide and prone to aquaplaning on water and slush but they make the car look better. A better tire would be 195-60R/16.
