Why can't the BRZ GT300 or factory BRZ wheels have flush fitment?

[switchlanez]

Prius GT300



Yet VWs like the Golf R have wheels that come more flush from the factory.



And LFA fitment is not bad.


What are the reasons for this?

[fatoni]

its probably a result of digging through the parts bin. with the gt, i just assume they didnt care too much as being flush isnt any faster

[OrbitalEllipses]

Originally Posted by switchlanez

Why can't the BRZ GT300 or factory BRZ wheels have flush fitment?

Because race car.

[switchlanez]

Originally Posted by fatoni

its probably a result of digging through the parts bin. with the gt, i just assume they didnt care too much as being flush isnt any faster

I would think it's a critical area of the car to engineer. Logic tells me it might have to do with brake cooling and ventilation. Front brakes typically experience greater load than the rears and the wheels on the Prius look more sunken in up front (unless the angle is throwing me off). But I'd like to hear what someone knowledgeable in the area has to say.

[Nardi330]

Becos tyres have drag and on a race car function > form

[Sasquachulator]

All cars are like this.......

Most if not all German cars are more flush with the fenders while every other make is not.

Ive come to expect it being some kind of German thing with their cars.

[serialk11r]

Originally Posted by Nardi330

Becos tyres have drag and on a race car function > form

I'd think the smaller the gap between the wheel and bodywork the less drag

See LFA. Hypermilers use plastic wheel well gap covers to close the gaps.

[switchlanez]

^Actually, I can see drag being caused by the tire on the VW in the area I circled below but that's due to the body curving inward.

But I agree there would be less air turbulence if wheels were more flush or, in this case, if the body were more flush with the wheels.

[fatoni]

Originally Posted by switchlanez

I would think it's a critical area of the car to engineer. Logic tells me it might have to do with brake cooling and ventilation. Front brakes typically experience greater load than the rears and the wheels on the Prius look more sunken in up front (unless the angle is throwing me off). But I'd like to hear what someone knowledgeable in the area has to say.

i dont think its that critical. i mean we complain when we cant stick huge rims under the wells and now we are complaining that there is a gap

Originally Posted by serialk11r

I'd think the smaller the gap between the wheel and bodywork the less drag

See LFA. Hypermilers use plastic wheel well gap covers to close the gaps.

what do you mean gap covers?

Originally Posted by switchlanez

^Actually, I can see drag being caused by the tire on the VW in the area I circled below but that's due to the body curving inward.

But I agree there would be less air turbulence if wheels were more flush or, in this case, if the body were more flush with the wheels.

i think the majority of the drag comes from the top of the tires since they are spinning in the opposite direction. there shouldnt be too much drag at the bottom as the tire is moving at the same speed as the air going past it. the top of the tire is dealing with twice the wind speeds in relation to the speed of the car

[serialk11r]

So kinda like a fender extension that goes into the wheel well...but mainly used on cars with a huge gap like trucks.

I think the tires spinning doesn't have that great of an effect, usually boundary layer thickness is cited as 1 inch or something. Not much air makes it to the top of the tire anyways. I believe most of the drag is caused by the very bottom of the tire, where air is getting "squished" out to the sides against the ground by the tire. Not sure why this is an exceptionally large source of drag but it seems to be. This is what wheel spoilers you see on all cars are for, directing the air away from the bottom front area of the tire saves more drag than it costs, and reduces lift more than it causes by damming up air before it against the underbody. The sides of the tire doesn't cause much drag as they're smooth, the rims cause a bit of drag though which is why the Insight for example has smooth rim surfaces and the rear wheel covered.

switchlanez you're right about the body curving in, it exposes the edge of the tire to the airflow.

I don't know how close the wheels should be when the slight pumping action of the spinning wheel and the effects of the rims are taken into account, but the LFA is probably a good reference as they paid quite a bit of attention to this sort of stuff.

[MRZ415]

being flush is not all fun n games ... it looks nice ...
but I went from Sorta-flush to NOT .. because it was hurting
my car ... I have fenders rolled with ET37 BBS VZ... and I rub-a-dub.

With the BRZ ... I rather stay stock ... suspension travel is a great thing...
for example I did not realize how much better my current vehicle handled
a corner untill I raised the coils up an inch or two from my Sortaflush stance.

[switchlanez]

I don't think this car will have as many fitment issues.

Originally Posted by MotorTrend

Just a peek into the FR-S’ fender wells revealed the car was designed with aftermarket wheels in mind. The inner lips of the front fenders are already smooth, meaning fender rolling won’t be required for that ultra-flush fitment. Both front and rear brake calipers are compact and flush with the wheel hubs, practically eliminating any clearance issues. The rear wheel wells are particularly roomy, since the rear shocks are inboard of the inner fender lining. Several wheel experts mentioned the possibility of fitting 10-inch-wide wheels in the rear with little to no modification.

[catharsis]

Better question. Who Cares?

[fatoni]

Originally Posted by catharsis

Better question. Who Cares?

kind of a stupid question considering that its safe to say that at least the op cares