Oversize Wheel and Tires – A Good Idea?

January 22nd, 2016

You see it all the time…either urban rides rolling on 24” or 26” wheels and low-profile tires, or 4 x 4 trucks on huge skins that allow enough ground clearance to Oversize Rims in Lafayette LAget the differential and exhaust over obstacles. There are pros and cons to both of these ideas….and they’re mostly “cons.” Here’s a brief rundown:

·         Larger wheels and tires are heavier. That means more rotating mass that has to be brought to a halt, and a compromise in braking performance, with more brake wear and longer stopping distances. On a truck, in particular, those big wheels tend to be much heavier can mean premature wear on suspension, steering and drivetrain parts. Premature wear on steering parts, in particular, will make wheel alignment difficult.

·         Taller wheels will throw off speedometer readings, by making the speedometer read slower than your actual speed. In addition, they can throw off the algorithms of your ABS system and vehicle stability controls, both of which operate by monitoring the rotational speed of each wheel.

·         Taller rims and tires can rub on the inside of wheel wells

·         Heavier wheels and tires can add to the vehicle’s “unsprung weight,” meaning the weight that isn’t supported by the suspension. Adding to unsprung weight can put new stresses on steering and suspension components, all of which were designed around a set unsprung weight package that came with factory wheels and tires.

·         Taller wheels changes the truck’s effective gear ratio, which will affect power, acceleration and fuel economy, and will change the transmission’s shift points. If you’re going to go with much larger tires on a truck, it’s a good idea to have the rear axle gears swapped to a lower gear ratio (which is numerically higher).

·         If you’ve got a car and you want to put 24” or 26” rims on it, remember that along with all the other drawbacks we’ve already noted, the low profile tires are going to have a much harsher ride. That’s not hard to figure out – their shorter sidewalls mean there’s less rubber to absorb the jolts and bumps in the road. It’s like the difference between sleeping on a nice mattress or rolling out a yoga mat and trying to sleep on it.

·         Wider tires (not taller) can give some improvement in cornering ability, steering response and traction, if that’s what you’re after. Much wider tires, however, will mean increased rolling resistance and poorer fuel economy.

 

Here’s the upshot.

Your car’s transmission, drivetrain, brakes, suspension and steering were all designed with a specific size wheel and tire as a prime consideration. Any change to wheel and tire size will have an effect on braking, handling, ride quality, road manners, wheel alignment and other factors, and the more radical the change in size, the more it will necessitate a re-engineering of the vehicle’s suspension and drivetrain. If you’re really wanting to go with tall wheels for your urban ride or big oversize mudders for your truck, you might want to prepare yourself for other upgrades to really make that work (or get ready for a lot of headaches).

We hope that answers any questions you might have about oversize wheels and tires for your vehicle. If you’re thinking you want to go that way, or if you just need a set of stock OEM-size tires, give us a call at Chabill’s Tire & Auto Service, make an appointment and let’s see what we can do for you!

  Posted in: Auto Repair 101