Effect of wheel offset
 

One of the things I have tried to understand but don't fully have a grasp on is the effect of wheel offset on the car's handling characteristics and steering feel.
From what I have read there are two main elements that will have an effect, track width and scrub radius. Supposedly increasing track width gives a little better grip and scrub radius changes steering feel (though frankly I am confused if less offset would increase or decrease that steering feel).

Could someone explain this to me? How much effect will a +35 rim have on our cars on the track?

Increasing track width will increase stability when vehicle weight is transferring from side to side, just because the car now has a wider base.

Having a lower offset will increase the scrub radius, which is the distance from the center of the tire to the point around which the hub pivots with steering input. In a perfect world, these two points would coincide and you would have no scrub radius, effectively meaning that when you turn the steering wheel, the tire pivots in place. In the real world where we do have scrub radius, when you turn the steering wheel you're basically dragging the tire through an arc centered on the steering pivot point. Increased scrub radius means you're dragging the tire through a bigger arc and covering more distance, which will make the steering system work harder because it has more friction to overcome. This will make the wheel feel heavier.

Not a lot though. I'm running 20/25mm spacers and I can't tell if the wheel is any heavier or not. I do take care not to crank the wheel from one side to the other while sitting still, because that's a lot of friction to overcome. When you're rolling it's not an issue though.

It's also worth nothing that spacers and offsets that push the wheels out place significantly more strain on your wheel bearings.

Not really. No more than wider wheels and tires or lower offset wheels do.

edit: Now, whether spacers are approved for track duty is another matter. That would be up to the tech rules for your racing association and the inspector looking at your car.

It's hard to find a car in the paddock during a race weekend that doesn't utilize spacers of some type.

I use a combination of no spacer, 5mm and 10mm spacers. I often run 10mm up front and non in the rear to widen my front track. (not the FRS)

What's going to get you into trouble in tech is if your spacers keep your lugnuts from engaging enough of the studs.

What about bolt on spacers vs. spacers that use replacement studs?

Version 1 w/ extended studs, of course.
Version 2 w/ bolt on.. I'm not sure. I've haven't seen a tech supp that specifically rules these out so.. :iono:

not directly related, but in karts (shifters) wheel spacing is a majority of overall setup

Small point, but that's not actually true. In a perfect world, you want a reasonable amount of scrub, because zero scrub makes the tires squirm when you turn. Some cars have positive scrub, some have negative, but either way it gives you road feel and increases steering effort the more you have. On a light car with power steering this probably won't matter until you get to a truly ridiculous amount of scrub. One effect you WILL notice, though, is that with a large scrub radius (lots of spacer) the wheel swings in an arc instead of pivots when it turns and you will rub in bizarre places against the frame / in the tub at lock.