Why Tall Wheels?
Q I’ve fallen victim to a bit of confusion regarding wheel and tire sizes, and I hope you can shed some light on this for me. In the past it has been deemed important to have a lot of sidewall, whether for mud or rocks. However, wheel sizes continue to get larger and larger, so a 35-inch tire on 16-inch wheel won’t have the same sidewall height as a 35-inch tire on a 20-inch wheel. Truck manufacturers seem to be moving toward larger and larger wheel sizes. I would have thought that it would have been just fine to stick with a 16-inch wheel, allowing for taller sidewalls on off-road tires.
I’m currently looking to put tires on my ’03 F-250. If I decide to use something other than the stock wheel, I’ll have to decide whether to stick with the OEM 16-inch wheels or move to a bigger wheel. But then I’ll lose sidewall height.
Can you please explain any benefits to the larger wheel sizes? Thanks.
A Larger wheel sizes are due to public demand, larger brakes being installed, and high-speed stability on the road. My personal preference is a 17-inch wheel. These seem to clear most brake packages and are the current standard amongst most OEM truck companies. Some 4x4s come standard with 18- to 20-inch wheels, so these may have even larger brakes that a 17 won’t clear. But if you have 16s and are looking to upgrade, I say get 17s. There are also a huge number of tires available for a 17-inch rim.
As for sidewall, the larger the sidewall the more flexible the tires, and in many ways the better they work off-road. But there is an extreme in both large and small sidewall that can hinder performance. An extremely tall sidewall may flex well but can feel wobbly, such as a 40-inch tire on a 15-inch wheel. An extremely short sidewall (say, a 30-inch tire on a 20-inch wheel) can give stable corning control, but also ride rough and allow wheel damage off-road. I usually vote for a wheel no more than half the tire diameter, but in most cases I’d go with a 17-inch wheel first.
It Ain’t So
Q I own an ’89 Toyota DLX Extended Cab 4x4 with 272,399 miles. The truck came out of Minnesota, so you can imagine all the rust. I want to get better mileage out of it, and I need advice on a great lift that will clear 33x9.50.15 BFGoodrich tires. I want to replace a lot of the old parts due to wear and tear. However, the engine, transmission, cooling system, and charging system are new. I also want to put a header system on it and upgrade the exhaust. I need the truck to perform well off-road but I want better mileage. Can you suggest a lift for it?
Fort Sill, OK
A There is no lift kit that will increase fuel economy, sorry. By raising your truck—or any truck, for that matter—you are giving it a larger front area to push through the wind. This and the rolling resistance of larger tires will hinder fuel economy, no way around it. Your best bet is to keep your truck stock and lightweight, with the tires aired up properly and the engine and drivetrain in proper running order, and drive gently.
Dessert Shafts Before Dinner
Q I have a ’78 Chevy Blazer, and I plan to upgrade the engine and the drivetrain. They tell me I have to measure the truck in order to order new driveshafts, but to do so, I would have to order the engine, trans, transfer case, axle assemblies, and lift kit and have them all installed on my truck, then do the measuring and order new driveshafts. The problem is I live outside the U.S., but I plan to order all these through suppliers in the U.S. I think there should be a more intelligent way to do the measuring and order all parts at once.
A Putting your drivetrain in your Blazer before you order your driveshafts is the best option. You could post your plan on the Internet on Blazer owners forums, or call Blazer specialists like the guys at Offroad Design (www.offroaddesign.com), and there is a possibility that somewhere out there you’ll find someone with the exact same setup as yours who can measure his driveshafts and you can order duplicates, but what if the measurements are wrong? Then you’ll have to do it all again and still wait. It’s possible that there is a slight difference between your truck and someone else’s, such as the springs don’t sit as high or the axle yoke is slightly different.
Take my advice: Sometimes you just have to build the truck to know what you need to build the truck. That’s why so many of us either build more than one 4x4 (we learned a lot from the first project) or never build another one (we got really frustrated from the first project). I understand that ordering all your parts at once would be great, but some items just need to be ordered after the drivetrain and suspension are installed.