ISNICE

New to my 2104 IS350 AWD F-Sport and new to this forum, but not new to cars and car forums in general.

I've been searching around on CL and I can't seem to find any information on the staggered AWD set-up that comes from the factory. Here's what I'm wondering:

1. What are the technical reasons for Lexus going with a staggered AWD setup?
2. I had an Evo X previously and I had it ingrained in to my mind how bad it was to run a staggered setup on an AWD car that was designed for a square setup. So.... would it be bad to run a square setup on an AWD car that's been designed for a staggered setup?

Thanks for your help.

corradoMR2

My guess is because the car mechanically essentially behaves like the RWD IS under normal power/non-slip conditions, so a staggered setup is therefore better overall for handling and stability. Under these normal non-slip conditions, 80% (I believe) of the power is always sent to the rear, unlike some AWD systems where it's more evenly split even during normal use. The previous 2IS AWD was the same system and it did not have a staggered setup, but suspension is different in the 3IS.

yycdave

It's 70/30 rear/front split by default.

Not sure on the reasons why, but those fat back wheels look awesome.

GrandSedanFan

iTrader: (1)

You're fine if you keep the outer diameters the same at all 4 corners.

If you're running a 255/40 front, you have to run a 285/35 rear. Use a tire calculator like the one on miata.net if you need help.

nabbun

What Panyo said. The keep the rolling diameter the same. You will damage the rear diff if it's over 1%-3% different. PM MikeZ. He has an 07 IS250 AWD with staggered Work wheels. If you do a search for staggered awd in the 2IS forums you might find more info.

ISNICE

Thanks for the replies.

Regarding the reason for the staggered setup, could it have anything to do with the engineers at Lexus trying to reduce front grip and thereby make the care more neutral/understeery at the limit, as opposed to it being more prone to oversteer?

Also, I understand the importance of keeping rolling diameter the same on an AWD application. But what about tire width? i.e. putting wider tires up front to match the width of the rear tires, but still having all tires with the same rolling diameter.

I'll check out the 2IS forums in the meantime....

ISNICE

I'm a bit confused by this. Your first sentence makes it sound like keeping rolling diameter the same at all four corners is the only thing that's necessary. But then you're second sentence seems to say that keeping the staggered width setup is also necessary too.

If as long as you keep the rolling diameter the same at all four corners as you said, then why is it also necessary go with wider tires in the rear if I want to increase tire width in the front? i.e. why can't I leave the rear tire width at 255 (stock) and go with wider tires up front (from 225 to 255) as long as the new wider fronts have the same rolling diameter (by having an appropriate aspect ratio) as the rear?

GrandSedanFan

iTrader: (1)

I was just using those specs to demonstrate staggered widths of the same diameter.

You can absolutely go square if you want to be able to rotate. On these cars, the staggered fitment is only for looks.

ISNICE

Ah, okay. Thanks for the clarification.

And so the staggered setup is strictly cosmetic? There was no deliberate technical reason for it on the part of Lexus? Interesting.....