Effect of Wider Wheel Stance on Turn Radius

[slow_c1500]

Hey guys, Im in the process of choosing my lift/wheel/tire setup for my truck, and I was wondering if having the wheels stanced out more (whether its from a spindle lift, offset, or spacers) would affect the turn radius at all (assuming I am not rubbing on anything)? I havent found the answer for such a seemingly simple question. Also wondering if bigger tire diameter would have an effect. Thanks!

 

[99xcss4]

it most likely dose at some point do not know how much or little though or the details either it is above my paygrade I am shore some one here knows all things you need to know about this

 

[Scooterwrench]

No,wheelbase determines turning radius. Spacing the wheels out may effect TR because the tires will rub the fenders and/or bumpers. If you lift the truck(body and/or chassis)the tires will clear again and you will get your original TR back.

 

[Schurkey]

Space the wheels/tires farther out, and that little itty-bitty outer wheel bearing on the front of 2WD trucks gets overloaded and fails early. Same principle on 4WD, but at least the bearings are larger. And same concept on the rear axle--pushing the wheels outboard makes life harder on the bearing in the axle tube, riding on the axle shaft.

It's also going to screw-up certain steering angles, (Scrub Radius, and Ackerman, for examples) changing steering effort, reducing stability if a tire goes flat or hits bumps, potentially reducing tire life.

Overall, it's a dumb thing to do.

 

[Sean Buick 76]

The more the wheel is moved out away from the Center of the wheel well the more the turning radius is decreased. A few inches likely won’t be able to even measure the reduced radius. 8” yes you will for sure notice the difference

 

[Erik the Awful]

Spacing out your front wheels changes your ackermann angle and will cause more tire scrub.

The Air Force uses bobtail trucks on the flightline. Basically, a bunch of body-in-white trucks get shipped to the conversion company, they chop the middle three feet off the frame, move the axle forward, install a heavy metal bed, and gear the truck to 40 mph. You get a crazy-tight turning radius and insane towing capability.

air force bobtail truck - Google Search

The last trucks we got before I retired were 2008 Ford F350s. The tires were only lasting a couple hundred miles before being scrubbed bald. The base motorpool tried writing us up for misuse and abuse of the trucks, so I wrote up a detailed explanation of ackermann angle and tire scrub, which shut them up. I don't know if the Air Force ever went back to the vendor to see about modifying the spindles. My guess is no, that requires paperwork, and new tires just cost more taxpayer money.

 

[Sean Buick 76]

What is Scrub Radius?​

The distance between the tire center line and the steering axis is the scrub radius. A positive scrub radius would have your tire center further out from your steering axis, in contrast a negative scrub radius would have your tire center inside your steering axis. The performance differences vary vastly with different scrub radius, but it is often found on OEM vehicles that scrub radius is close to 0. So a wheel with a more negative offset would net a more positive scrub radius. A “0 offset” wheel may or may not net a 0 scrub radius, depending on the size of the tire. Yes, the height of the tire also comes into play when calculating scrub. Taller tires actually help the scrub radius when using a more negative offset wheel.

From this article. A negative offset wheel makes for a larger turning radius.

Steering You Straight: What is Wheel Offset and Scrub Radius?

If considering larger wheels and tires for your off-road truck, you'll need to figure out offset and scrub radius so you don't screw up your steering.

www.drivingline.com

 

[Cadillac Bob]

So I have 20x9 wheels and 275/55 R20 tires they’re about 11.5-11.75 wide and that’s stock ride height straight bolted on. There’s just a little room left a once in a while rub but that’s at lock and a bumpy road. Here’s a few pictures of to show the fitment and one with the stock wheels on to see the difference

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[slow_c1500]

Thanks for the responses! I was thinking of doing lift spindles, which stance out the wheels about 2 inches. Would these negative effects still apply to spindles, or only to offset wheels/spacers? I can understand the latter causing increased wear and tear on suspension components, but the lifted spindle is the suspension component lol...

 

[Schurkey]

The suspension angles depend on the location of the ball joints in relation to the tire contact patch. The steering knuckle (not "spindle", which is part of the steering knuckle) probably doesn't change the location of the ball joints.

It doesn't matter if the tire contact patch gets moved outward due to the wheels, or due to the steering knuckle.