Purpose of big tires/rims

Do big tires provide any benefits other than perceived improved aesthetics? I would think the larger surface area would increase friction and traction (while also reducing gas mileage), but I have no idea if this is actually the case, or if it is the case, if the differences are anything other than de minimus. Do the provide a smoother or less smooth ride?

The link didn’t really answer the question, so I’ll try. Yes, big tires will provide more traction. They’ll also improve ground clearance, which is usefull for off-roading or driving through snow. With my Jeep I’ve never been stuck in my driveway no matter how much snow the city plow pushes onto it. Also they can handle more weight.

You’re right in that they give more traction and worse gas mileage, and also turning a heavier wheel/tire takes more power too. But I’m not clear what type of vehicle prompted the question. Some people put huge wheels and tiny tires on cars for the looks. They use tiny tires in order to make room for the huge rim. If you’re asking about something like this, it’s all looks (and possibly some mental disorder). They would theoretically have more traction but they probably drive so much worse that whatever gains in traction are not worth it.

Fast cars, like the Corvette or Porsche, often have larger wheels in the back for traction, and trucks or vans that carry a lot of weight will have larger tires because they can handle more weight.

Offroad vehicles have them because they improve traction and ground clearance. Some people air them down to lower pressures to get a bigger footprint and even more traction. Tthis illustrates it, and it’s common to air down to 4-6 psi. The larger the tire, the larger footprint you get when airing down. In this case, you usually want to stick with smaller rims so you can have more rubber, so a lot of offroad vehicles with huge 44 inch tires run something like 16 inch wheels, as opposed to the car above that has 25 inch wheels and 2 inch tires.

If you are referring to big rims coupled with skinny tires: low profile tires have less flex in the sidewalls, which adds to stability in corners.

At the expense of tire wear.

Could a person improve gas mileage by using four of the tiny spare tires?

Big rims = more space for bigger brakes. If you’re in the habit of driving at 200mph, this is a good thing. Otherwise, not so much.

You can’t go over 50 mph and they only have a life of 70-100 miles.

I would also like some clarification from the OP about exactly what type of “big” tires we’re talking about here.

I put big tires on my pickup truck. They are technically off road tires but are designed for use on the road. The larger size and more aggressive tread means that they will give much better performance in snow or mud. I’ve driven through a blizzard on back country roads that hadn’t seen a plow truck or any other traffic on them and didn’t get stuck, so they do their job.

The down side is that the gas mileage on roads is worse. Also, the tires both cost more and wear out faster than “road” tires. So not only do I spend more in gasoline, but I also spend more in tires in the long run as well. My truck is my bad weather vehicle though. I don’t drive it much in the summer, especially since the air conditioning doesn’t work on it.

Another thing I noticed on a smaller pickup truck that I used to own was that switching to larger tires made the truck more stable at higher highway speeds (65 to 75 mph). I am assuming this is due to the gyroscopic forces of the larger tire/wheel mass.

If you are talking about big rims with smaller sidewalls, that is done mostly for styling these days. You end up with a tire that is roughly the same diameter when measured from the outside of the rubber and not from the rim, and as long as the footprint on the road isn’t that much different then it won’t make much of a difference with respect to the rolling friction (and therefore the gas mileage).

Bigger rims combined with smaller sidewalls got its start in sports cars, where the shorter and therefore stiffer sidewall gives you better performance with respect to cornering (imagine the tire as a big balloon and you can see that a smaller balloon won’t squish to the side as much as a bigger balloon when you go around a corner). Since the “sporty” cars started doing it, other cars started following suit so that they would look “cool” as well. The problem is that with shorter sidewalls your ride goes to crap. Sure, you get slightly better performance in cornering, but you feel every bump since you don’t have as much of an air cushion under your rims. So basically you end up with a bone-jarring ride and faster tire wear just so you can have performance cornering in a car that you probably don’t drive for performance anyway (most folks keep within the speed limit, or at least reasonably close to it, on their way back and forth to work). Seems a bit stupid to me, but that’s just IMHO.

There’s always a tradeoff though. Tires designed to give you the best gas mileage are going to be horrible in rain or snow. Tires designed to give you the best grip for performance on dry pavement will also suck in rain or snow. Tires designed for rain don’t necessarily do well in snow, and tires designed for snow don’t necessarily do well in rain. In the more southern areas of the U.S. folks just drive on one set of tires all year round. These “all season” tires are designed for fair performance in dry, wet, and snowy weather, and because they are a compromise, they don’t do particularly well in any one condition. In more northern areas, folks will drive tires that are better in dry and rain conditions but suck in snow in the warmer months, then switch to snow tires for the winter. Tire size factors into it, but it’s only one aspect of tire design. Tread thickness and design makes a huge difference as well, as do other things like the formula of rubber used.

Hi. First time poster, long time lurker. It took a post I actually have some opinion/knowledge about to actually register.

If OP is referencing the fad of Chargers or Crown Vics with 26" wheels and rubber band tires, there are MANY negatives and few, if no positives.

Negatives: worse gas mileage, diminished braking/acceleration/cornering due to higher inertia of bigger wheels, suspension dampers are overworked (causing a bouncy ride) because of the higher unsprung mass, oftentimes decreased steering angle, higher drag coefficient since most of the time these tires are much wider than original

The only positive I can think of is the flywheel effect they would exhibit. Once at some speed, it becomes easier to cruise at that speed since the wind/road resistance is working against a heavier spinning mass. This is why offroad vehicles and big rigs have REALLY heavy engine flywheels. Increased rolling resistance, however, likely cancels any such affect.

These wheels and tires do have stiffer sidewalls, but these tires are by no means performance oriented. Aside from that, the heft of these wheels makes it pretty much impossible for the car to handle any better than the stock small wheels and rentacar tires.

The skinnier the tire (of any type), the less rolling resistance and the less rolling resistance, the more MPG. Look at any vehicle that competes in Drag Racing. The front tires are always skinnier and inflated to relatively high psi. The caveat for street driving, however, is the loss of handling and braking capability. Like almost anything in life there is a point of diminishing returns.