I have 245/35/20 and 275/30/20 if i use only summer is this ok for my gs?

 

No good at all! The rolling diameters are way off. Your gonna have to do some research on the tire sizes. Go to 1010tires.com you will be able to put in different tire sizes that would get you close to the stock RD.

 

I have the same car and running 245/30/20x9 and 285/25/20x10.5. I believe that is the recommended size for my rims.

 

245/35 is too big for the AWD. you must keep the overall diameters within 2% of the stock diameter to avoid damage to the AWD system (at least told to me by a lexus tech)

 

actually if front and rear got bigger together but close to each other, it's fine. again the car has no way of knowing what overall diameter you using. key is to match front and rear diameter closely, not necessarily matching factory diameter

ideally you want 245/35/20 and 285/30/20, that's overall 1" larger in diameter both front and rear from stock. but good luck dealing with all the rubbing issues

personally i would still recommend 245/30/20 and 285/25/20

 

Now i have tsw 255/3519 all around. I want some big rims for rear.. So its not good for awd with that size--245/35/20 and 275/30/20?

 

your post is confusing. you want some bigger rims (20) for just the rear?!

 

Yes i want big rim for rear

 

do you mean WIDER rims?