Wheel Design Questions

[raildogg]

Looking, recently at adds for wheels in car mags and noticed this, the spokes for 90% of them were very close to the edge of the rim. This caused me to ask myself, what about offsets. What are the determining factors for the offsets?.

Is it that the tires want to be centered in the wheel wells or, do they need to be centered at all? On say, 1/25th scale models, where is the offset, center, front or back. Do they actually emulate the prototypes arrangements, or do they fit the models geometry?

I would like to design some wheel rims for possible 3d printing and I think, this would be an important design feature to consider. Please comment and expand this idea for me. I need to know so my sketches could have some relevance to them.

[Ace-Garageguy]

There are several criteria that determine wheel offset on 1:1 cars, and for FUNCTION, best design practice strives to produce a wheel that places the center of the tire contact patch roughly in the center of the wheel bearings at the rear, and at the center of the steering axis in the front.

Various offsets are necessary to accomplish this depending on the type of suspension system employed, the design of the bearing carriers or spindles, and whether the car is front-wheel-drive, or rear-wheel-drive.

Model cars that are models of existing vehicles usually get this pretty close to right, but not always.

Deeper or different offsets are employed in custom aftermarket or racing applications, to go for a specific 'look' that fills the wheel well, or to allow running wider tires.

Offset explained (backset is also referred to as back-spacing) http://cocomponents.com/dealer/blog/wheel-offset-explained/

Edited January 26, 2014 by Ace-Garageguy

[pharoah]

Couldn't have said it better Bill.

Aren't most new cars designed with positive offset? Maybe because most are front wheel drive?

[o-man]

Couldn't have said it better Bill.

Aren't most new cars designed with positive offset? Maybe because most are front wheel drive?

No. Mustangs have positive offset wheels. I don't know enough about suspension geometries, etc. I'm not sure if any new non-specialty car that has a negative offset.

[raildogg]

O.K., so if I take all this and said, I can, make a ring rim, and a spoke section, and make it user adjustable would that be something I could highlight as, " a design feature"?. Since most scale models seem to mount wheels on backing plates, or simulated brake drum/disc points.

[pharoah]

I've seen some model wheels (somewhere) that consist of a rim and a center piece.

Like you said,the center is adjustable for offset. If I remember right,the rim was aluminum ,and the center was resin.

Seems like they were big scale too.

[raildogg]

Well, this idea seems like it's been done already ( see post in resins). I guess I'll just do it for myself with designs I want.