How is the handling and safety effected with vehicles having those large diameter rims and the small tires?
The wheels and tires that come standard on a vehicle are a compromise between handling, durability, ride smoothness and cost. A lower profile sidewall improves the tire rigidity (and consequently the handling), but adversely affects the ride quality. The idea is to maintain the same overall tire diameter by going with a larger rim with a lower profile tire. This combination improves handling and traction without adversely affecting vehicle dynamics. In the instances where you see extra large rim and tire combinations (sometimes referred to as wagon wheels), these are strictly for show. They raise the ride height and center of gravity and adversely affect handling.
In a lot of cases, yes, the wheels are just for bling-bling (or Rice, depending on the vehicle), especially if the car had to be jacked up to do it. I saw an old Chevy Impala from the late 1970s rolling around on 25″ rims not too long ago. I doubt if the owner set it up that way to improve handling. Consumer Reports warns against this kind of modification: However, if you take a look at a performance car, like a Mercedes-Benz SL, you’ll see the larger, wider rims with low profile tires as standard equipment. Within limits, they can have a positive effect on cornering, as the lower profile tires are less likely to roll under when the car is pushed to its handling limits. A wider, low profile tire on a larger rim also improves full-throttle acceleration and braking, particularly when mated with a high-performance summer tire. The down side of upsizing rims and tires is a harsher ride and reduced load limits. For a Honda Civic, this might be a non-issue, but you wouldn’t want this on a li
If the large rims and tires change the loaded radius (the distance from the center of the axle to the ground), front geometry goes out the window. The chances of decent handling are nil. If the tire width changes or the track width changes, you will have handling changes. Again, the chances of an improvement in handling is nil. If any of the geometry isn’t changed much, the handling should be ok. The larger rims tend to be stiffer, giving better cornering and a bit rougher ride. They also reduce the unsprung weight, which gives better traction, if the shocks are up to it. You see how much the NASCAR pros monkey with the suspension. It should give you an idea of how complicated good handling really is. Factory suspension setups are pretty conservative. Check the blogs for someone’s experience with a given setup or suggestions for the changes you have in mind. Happy motoring.
