The question is in the subject, What’s the difference in size of car wheels? I’ve been looking at cars to buy once I graduate school, and I notice in many cars they offer a larger size wheel, 19" vs 20" for example, as an option.
Well, my question is, what is the advantages and disadvantages of a larger size wheel if everything else stays the same? Why would something larger cost more?
Mostly, larger wheels look cooler (depending on your taste). Because they look cooler and are considered an upgrade, they cost more, but of course there is more metal there also. It can be argued that larger wheels, which result in smaller tire sidewalls, reduce sidewall flex and therefore improve handling. However, that is really a non-issue for almost everyone who is actually buying these cars, and even for people who might care; maybe if they plan to take the car to the track; the differences between the standard and upgraded wheels are rarely significant.
Besides higher cost, larger wheels also will give you a rougher ride and be less resilient to things like potholes. More flat tires. But they do, within reason, look nice. It can be taken too far, and often is.
In principle larger wheels provide greater clearances allowing larger brakes - which might be important if you have a car intended for continuous extereme high speed driving. But upgrading the wheel beyond the basic design size does nothing, since the brakes didn’t change. So larger wheels look a bit like the wheels on that Ferrari or Lamborghini. But serve little actual purpose.
It is also an interesting issue about sidewall height. Look at a real race car. They don’t run ultra low profile tyres. The nasty little secret is that ultra low profile tyres are actually slower on the track. They can aid a sharpness in feel, but for the most part impart essentially no actual performance advantage, and indeed reduce ultimate performance. About 50% profile is the sweet spot.
They form part of what I call “playing dress ups” for car owners. People under the illusion that they need a “high performance” car, where high performance is ill defined and is mostly a reflection of marketing and ego. There has been a steady trend in marketing cars with “sports” features, which translates to hard suspensions, low profile tyres, aerodynamic features, all at extra cost, and which ironically result not in a better car, but actually one that is an inferior car for purpose.
I mostly agree with the others, bling. Add to the short, stiff sidewall, a harder rubber compound in the tire, and the ride is even worse. The result is a vehicle that can generate amazing G forces in the hands of a skilled driver on a dry skid pad, but doesn’t stop near as well on a wet road. The interesting thing is that as the wheels get bigger, with the outside of the tire staying about the same, the ‘‘bigger’’, more expensive tires only have a bigger hole in them.
We have cars better suited for sustained speeds of over 100 miles per hour on dry roads than for real world speeds on wet pavements. -Some of the more expensive tires do offer better wet road traction.
The added cost could also be related to the price of the tire. Tires that fit larger rims and that have short stiff sidewalls are usually more expensive than a tire for a smaller wheel and taller less stiff sidewall.
I always heard that larger tires provided a smoother ride, not the other way around.
You are probably going to opt for the larger wheels as they look cooler. Along with the larger wheel size comes a lower profile tire in most cases. They handle slightly better, but I think they look ugly. And what bothers me most is the fact that you have less tire between you and the road. That makes a huge difference in pothole country where I live. People routinely blow those tires here and bend the rims as well. The damage can be hundreds. I’m completely for bigger rims as long as the tires maintain a high profile. That gets me off the road even further.
(Me in a GMC with huge tires.)
Bigger tires of the same profile or aspect ratio will give a better ride within certain limits. However, the current fad of tires with really low-profile sidewalls give a harder ride than stock tires usually, since sidewalls give the tire its shock-absorbing qualities, and tall sidewalls are better than short ones at absorbing road shocks.
We have a car in which we have summer tires and winter tires. IIRC, the summer tires are 17 in and the winter tires are 18 in. I have no idea why/how, all I know is that my husband wanted different tires for different seasons rather than going with an all-season tire.
Most people in this tread are talking about large wheel rim sizes not larger tire sizes. The outside diameter of the tire generally stays the same for a given model of car. With larger rim size the height of the sidewall, basically the “size” of the tire goes down. So the 18" wheel has a smaller tire “size” than the 17" wheel. So what you heard is basically correct.
A dedicated winter tire will be dramatically better in snow and ice than an all-season tire. A dedicated summer tire will be better (though perhaps not dramatically, especially for normal driving conditions) on dry roads than an all-season tire. If you live somewhere that you have to regularly drive in bad winter conditions, it makes sense to have real winter tires. And if you’re going to swap your tires seasonally anyway, you might as well go with summer tires in the summer to get the benefits on both sides.
For new cars, manufacturers also tend to put cheaper tires on the small “cheap” wheels, and better tires on the “upgraded” larger wheels. In other words, the cheap base package will have cheap tires that sacrifice some combination of traction, ride comfort, or fuel efficiency. Of course you can put on better tires yourself, and if that’s all you’re worried about it might be a better option than getting the upgraded package with lots of other stuff you don’t necessarily want.
Here’s a similar thread I started last year on this.