Picked up my Obsidian 350 AWD this weekend and already thinking about upgrading the stock 17" wheels but I wanted to know if anyone could explain why the AWD version comes stock with 17" wheels and how does this affect picking the new rims.

 

all ISx50s come with 17" wheels stock. 18's are optional.

The only thing different with AWD is the 18s are the same size (18x8) while on RWD models the 18s are staggered (18x8 front, 18x8.5 rear).

AWD needs the overall diameter of each wheel to be the same or it'll mess up the AWD system

 

one can also run staggered wheels if they use specific tire size that minimize the overall rolling diameter, you can use this calculator

http://www.1010tires.com/tiresizecalculator.asp

i am running staggered is350 wheels on my awd while running 225/40/18 size tires, rear tires are stretched a little bit but not a lot, so far no issues

 

AWD's always have 17's, 18's are not an option on any of them as far as I know.

Jeff

 

For US, it is optional. Most likely no one really selected this, but essentially can get one like this.

 

I don't think it is, at least not from the factory. I know they offer port (Japan/USA)/dealer installed 18" options like the X-Package wheels, F-Sport, G-Spyder, etc., but that is all done after the fact.

I mean I guess it doesn't really matter, since when the customer gets the car, they have the wheels, but when they leave the factory, they all come with 17-inch wheels.

Jeff

 

Factory specs from the NCF books from 2006, 2009 and 2011, as well as the EPC wheel information for PNC 42601 (Wheel), for MY '06-10:

2006:


2009:


2011:


MY '06-10 GSE25 (IS250 AWD) EPC:


Jeff

 

OP asked "why" does the AWD come with the 17"ers. I have two guesses.
Since the AWD has a raised suspension, adding the 18" to it would jack it up too high.
Or my next best guess would be smaller tire gets better traction in the snow than a larger one. A smaller footprint puts down more weight on the contact patch, creating better grip.
Just guesses.

 

Jeff, the 18x8 F-sport wheels are optional on the AWD models-

http://www.lexus.com/models/IS/features/pricing.html
$1756 MSRP.


I realize this might be port installed rather than factory installed, but it doesn't make them any less of a new-car option from the perspective of buying at the dealership.

 

Oh yeah, actually that reminds me, Lexus Canada does not have the F-Sport 18" forged wheel available, only the 19" for RWD.

 

Larger low profile tires give a harsher ride and I have been told the 17"s handle better in the snow and ice.

 

^
True. Unless one does not mind that's a different story.

For me, my car has stock 18" and originally was thinking of going to get 17" wheels and Blizzaks. However after talking and getting some advise, it was more worth it by keeping my stock 18" to and use Blizzaks and get forged 18" wheels for summer tires instead.