Experienced effects of negative offset

[blue22]

Hello,
Please point out if this has been discussed in thread I missed…
I have 2022 bronco base that is stock. They I bought a cheap set of castoff wheels and began adapting. I did not account for the effects of -14mm offset in regards to scrub radius. Will this be as bad for my bronco as some of my research suggests?

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[Brian_B]

You will notice it for sure

as far as “bad” goes … it won’t instantly break anything but it will be harder on your steering. And throw more rocks/mud because of the poke

 

[SierraBronco]

@87-Z28 could run some calculations to tell you how much additional scrub radius you’ve created. But really I personally don’t think you’re going to notice it too badly. Not sure what your factory offset is, but with Sasquatch wheels of +35mm (or maybe 30. I always forget) going to -14mm moves you out about 1.93 inches. I have 1.75” spacers on one bronco and don’t notice much if any difference with the factory tires. Now, our big bronco with 3.75” spacers and 40” tires-that’s a different story.

 

[87-Z28]

Wheel offset will determine the moment arm (leverage) applied to the steering (kingpin) axis. Increasing this leverage will most definitely increase loads along load path from tire contact patch to frame. This includes wheel bearings and ball joints. The primary load carrying members (knuckle, UCA, LCA) can handle increased loads. The main concern would be additional long term wear and tear on the wheel bearings and ball joints. Nothing will explode.

a perhaps more significant concern would be the increased loads acting on the steering rack through the tierods when this leverage is increased. You will not likely be able to notice any increased steering resistance on pavement. Where this may become a more significant issue is when pushing the steering rack to its limits in more challenging terrain, deep snow, sand, mud or other terrain that may challenge the rack.

Both scrub radius and mechanical trail are needed to fully define this (3D) moment arm. In a simplified 2D sense, scrub radius is usually the primary metric used to evaluate steering resistance. The oem designed scrub radius is very small, <1 inch. You can calculate your current scrub radius from the attached formula. Don’t be alarmed if your scrub radius is rather large. Nothing will explode. It is just good practice to try and minimize scrub radius.

Just bolt on 50” tires.

 

[blue22]

Thank you! This will be my “on road” setup and was done mostly for appearance and to “use up” my stock 16” tires. I have black diamond castoffs for off roading. Any other input would still be appreciated!

 

[BUFF]

i admit I changed my offset on my Jeep to get more poke. I did a lot of changes to the suspension that later caused the death wobble. I was able to fix the problem and it ran great. But the question is for how long. The vehicles are highly engineered and there can be cause and effect when you start making said changes. it can also cause you to have your warranty to be null and void on parts of your vehicle. So when I looked at Broncos I looked at the both the Raptor and wildtrack versions. i found the Raptor had what I wanted when I left the dealership. My point is know what you are getting into by making all the changes to the geometry of your ride but expect it to be money pit when things go wrong. And please don’t complain when things take a turn for the worse. Enjoy your ride.

thanks to 87-Z28 for the great diagram and explanation.

 

[blue22]

I wanted to keep original post succinct. Here is more info:
Original setup on 2022 ford bronco base:
255/70/r16 tires on 16x7 steelies with +55 offset
Proposed setup:
255/70r16 tires on 16x8 wheels with -5 offset and 3/8 hubcentric spacer to keep wheels from touching calipers and adapting to 108mm wheel bore. Rendering a 14.53 offset.
A website called rim and tire store configuration shows a 70mm scrub radius

 

[blue22]

I also realize this is posted to a bronco raptor forum. My apologies

 

[Oldhippie]

With all the folks running 0 offset without problems (including myself) I wouldn’t worry about it…

 

[swamp2]

With all the folks running 0 offset without problems (including myself) I wouldn’t worry about it…

Me too. 0 offset adds about 1.5" of poke per side in my Raptor. The only very minor downside I observed is that my front tires squeal quite a bit easier when cornering at low speed on road.

 

[87-Z28]

SAS scrub radius is 13 mm. (35s on +30 offset)

37s on 0 offset (a popular combo) 37 mm scrub radius

OP wants 30s on -5 offset (must be a typo) which has a 68 mm scrub radius. Almost double the 37s on 0 offset combo.

Probably not a big concern but I wouldn’t run the OPs combo. i Just don’t understand the desire to have some poke, unless trying to fit larger tires.

 

[blue22]

No not a typo. I found a set of alloy 16” bullet hole wheels with -5 offset cheap. I mistakenly thought I did my due diligence and all my research told me they would work. However after purchase and buying ring adapters the mounted wheels jammed solidly to pad carrier on the brakes. Doh! So then that brought me to looking into a 3/8”hub centric spacer that relieves bind and adapts hub and bore. That 3/8s now effectively changes my offset to -14.525. This now brings into question the scrub radius problem and hence my post.

 

[SHANUT]

Hello,
Please point out if this has been discussed in thread I missed…
I have 2022 bronco base that is stock. They I bought a cheap set of castoff wheels and began adapting. I did not account for the effects of -14mm offset in regards to scrub radius. Will this be as bad for my bronco as some of my research suggests?

I’ve been running wheels on my F250 for 30+ years that are larger, heavier, and stick out further than Stock and I have never had to do anything to that truck since new. Everything except for the tires, wheels, and 2 inch level is still original from 1994, including the shock absorbers. It still runs, drives and performs like new. And this vehicle was used to haul our large camper and haul wood to heat our home for many years so it hasn’t had an unusually easy life, but it has been well taken care of. As long as you don’t treat your things poorly you’ll be fine.

 

[Brian_B]

I’ve been running wheels on my F250 for 30+ years

They don’t make em like they used to

 

[SHANUT]

They don’t make em like they used to

I hear that all the time and I love my old vehicles and they’re all unrestored and in like new condition but my new vehicles are better in absolutely every single way.

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