GR Yaris ET 30

sixtentouge

Totally Hooked
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My car will never see a track, or competition. It's 100% winding road. Slow in-fast out. Doesn't need more traction than stock, as you can't get anywhere near 100% safely. In fact, it needs less traction to make it a bit more fun. If it really needs more grip, it's nothing a stock-size A052 or AR-1 won't solve.

That said... I'd really like to car to look better, bringing the wheels out some, but not at the expense of running giant 9.5" wheels. I see there are a lot of stock-width ET30 wheels out there, but was uncertain about how it would handle, with some people saying it will ruin the handling. So before committing. many thousands on a set of wheels, I bought a set of Digicam 15mm spacers to try out the ET30 offset.

Everything in the suspension is stock RZ High Performance (Track Pack). I picked a road near the house, and went back and forth on the spacers two times. First run stock, then spacers on, back to stock, and spacers on. It was a lot of work... No data. Don't really care, only interested in how the car feels.

First thing, the steering is a bit heavier. Noticeable, but not bad, and bumps are a little less jarring.

The good:

Turn in feels really good. Sharp.
Noticeably less body roll, especially on snap steering. The front corner doesn't dive as much and feels a lot more predictable.
High speed (100km/h) steering feels a lot better. Like if changing lanes very quickly, the car feels less "floaty," and more "on rails."
Doesn't follow ruts or grooves in the road. I thought it would with the increase in positive scrub.

The Bad:

It picked up a little understeer on heavy-throttle corner exit. All TC off (long push), but I never took the car out of "normal" mode for the AWD. "Track" mode may correct some of this, but the bottom line is that it understeers more than the stock ET45.

Your roads may vary :giggle:



I've settled on a compromise, and placed a back-order for a set of WedsSport SA-99R PSB 18x 8.5J+35. Might run the stock tires...we'll see.

Also on the table was a set of custom-valved Ohlins, but it's hard to justify that kind of money when I just don't need to go faster. Talking to someone from a GR Garage who sets up GRY rally cars, I've ordered and will try a set of RSR Ti2000 springs on the factory dampers. 40nm front and 42nm rear. Down 20mm. Will report back. Really hope this doesn't completely unsettle the car...

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my 2c is that if you like to slide the car and stuff, don't use too wide tires. Car feels much more nible and agile with narrower tires.
But with the looks requirement its of course different.
 
my 2c is that if you like to slide the car and stuff, don't use too wide tires. Car feels much more nible and agile with narrower tires.
But with the looks requirement its of course different.
This is why I was interested in the wider offset. Would like to keep the car on 225s, but don't want to ruin the handling for looks.
 
I run 18x 8.5j +35 Weds but on 245s. Sacrilege for some people but it’s better suited to the roads in my vicinity. I’m hoping that adjusting the camber a little when running a lower offset wheel, might bring some of that nimbleness back etc.

I guess not-so good quality tyres could also be a good option to get things sliding in a pleasing way

Work in progress!
 
Scrub radius is affected on the front, rear makes no difference. On our track Fiesta we went with less offset to get the tyres out to the edges of the guards and spacers on the rear as well. On the track with non road legal tyres it was not really noticeable because you are fighting the car everywhere anyway. A mate did the same on his road car with semis and it was awful. The front was slow to respond and felt heavier and the understeer was much worse. I did ponder going for stock offset in the front and 30 in the rear when I bought my road wheels but that precludes front to rear tyre rotations. Spacers aren't legal here unless oem fitment. So I stuck with stock offset and width though I am running 235s.
 
Scrub radius is affected on the front, rear makes no difference. On our track Fiesta we went with less offset to get the tyres out to the edges of the guards and spacers on the rear as well. On the track with non road legal tyres it was not really noticeable because you are fighting the car everywhere anyway. A mate did the same on his road car with semis and it was awful. The front was slow to respond and felt heavier and the understeer was much worse. I did ponder going for stock offset in the front and 30 in the rear when I bought my road wheels but that precludes front to rear tyre rotations. Spacers aren't legal here unless oem fitment. So I stuck with stock offset and width though I am running 235s.
Well a Fiesta is fwd.... And so is a GRY, also

One needs to drive pretty aggressively to notice the front drive, but if you do so on rutted roads, you will notice a changed scrub radius... It's just physics. I already notice on et40 and camber bolts, but only 205 width. Et30 on say 245 would be pretty awful. YMMV
 
Well a Fiesta is fwd.... And so is a GRY, also

One needs to drive pretty aggressively to notice the front drive, but if you do so on rutted roads, you will notice a changed scrub radius... It's just physics. I already notice on et40 and camber bolts, but only 205 width. Et30 on say 245 would be pretty awful. YMMV
Yea, something I forgot to add is that on a less than optimal surface, the ET30 picked up some first and second gear torque steer, as well. Nothing bad, but it wasn't there when stock.
 
Scrub radius is affected on the front, rear makes no difference. On our track Fiesta we went with less offset to get the tyres out to the edges of the guards and spacers on the rear as well. On the track with non road legal tyres it was not really noticeable because you are fighting the car everywhere anyway. A mate did the same on his road car with semis and it was awful. The front was slow to respond and felt heavier and the understeer was much worse. I did ponder going for stock offset in the front and 30 in the rear when I bought my road wheels but that precludes front to rear tyre rotations. Spacers aren't legal here unless oem fitment. So I stuck with stock offset and width though I am running 235s.
Could scrub radius be zeroed in with altering the camber? As negative camber is increased there will be a reduction in scrub radius. A minimal amount of change but some none the less?
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Could scrub radius be zeroed in with altering the camber? As negative camber is increased there will be a reduction in scrub radius. A minimal amount of change but some none the less?
View attachment 24784
If you add camber through the top mounts it doesn't change scrub radius. If using camber bolts, the tyre will move outwards at the bottom while the steering axis remains the same, this increasing scrub radius in the positive sense.
 
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