As I read this a thought occurred to me about checking your gas mileage. I've not tried this yet but it might be interesting to test out.

My portable Garmin Nav has a built in trip computer, and I find it very accurate for MPH and Miles driven. If you had one, or could borrow one, for a tank full you could find out how many miles you've driven and manually calculate your MPG at your next fill up.

Might also be interesting to see the difference in miles from the GPS to your ODO.

Just a thought.

 

Dont sweat it Mike! I too will be going staggerd.. 20x8.5 and 20x10 lol

 

I dont have a gps unit, but I will google map my destination next time then fill in a few gallons and see how it goes from there..

Sickness! You are going to beat me in terms of insanity level haha

 

maybe a little bit drop only

 

because the tire sizes you posted would change the diameter of the wheel/tires

 

lol. my average on this tank of gas was 10.4 mpg... so i wouldnt worry

 

This is why I haven't gotten the is-f

PEDAL TO THE fkn FLOOOOOOOOORRRRRRRRRRRRRRRRRRR!!!!!!!!!!!

 

i've seen my mileage go down also. with the larger wheels there will be a larger rolling resistance. check your pressures that can also have an effect on mileage.

it is fine to stagger an awd car as long as the front and rears have the same rolling diameter. i am running the same size tires and the front to rear rolling diameter at .01% difference. with upgrading rims the overall diameter from the stocks of course will increase slightly. since this is the case i have noticed my revs drop on the highway about 300rpms. the car knows it's traveling at xx speed and knows what the fuel flow rate is.

i guess the lower mpg is all about looking ballin' haha.

i'm just gonna live with it, i'm averaging 20mpg mixed 50/50 where before i was at maybe 23mpg. and that's at about 80mph on the highway.

 

Insignificant unless its from 255 rear to 305-325 rear.

 

Finally went staggered on my AWD today. Plain OEM R18 rims from IS250 Sport and Michelin Pilot sport sp2 tires 225/40 front and 255/35 rear. Drives really nice.
There shouldn't be any troubles if you keep the wheels diameter close to equal. For example BWM 325xi (AWD) goes with 225/40/18 front and 255/35/18 rear in stock. Default torque dispension for Lexus is 30 front 70 rear, for BWM 37 front and 63 rear. So I think we should be fine with our AWD staggered properly

 

But like Kurtz and I mentioned before, there is MOST LIKELY a BIAS programmed into the ECU for staggered setups that come stock.

But hey, it's your car.

 

Thats weird. i'm on 19's and i run 225 fronts and 265 rears and my mpg is just fine. Its like i'm on stock. But the most important thing to me, is checking the tire pressure. I'm always at 40psi, and i check it weekly. Remember if you have a three piece wheel it will always leak somehow if you let it sit too long. But anyways, i think if you drive a luxury car (Lexus) you shouldnt be complaining about gas. but thats just me

 

Yep I maintain mine at 40psi at all times, maybe its a lost cause for me. I work during college to pay for my car so the gas money after car payment, mods, and girlfriend becomes a rather fine art of driving slow, saving money, and skipping on lunch during the day


If you want to talk about the "programmed" bias then you should think about the % error the bias will have to over look due to tire pressure difference front and rear causing different rolling diameter, tire wear front and rear causing different rolling resistance front and rear, front and rear load to cause different "deflation" in the front and rear tires, all of those are no difference than the .7" inch in rolling diameter difference on my setup, its all within a given threshold.

 

^^^ oh ok, i can respect that bro.. My bad.. Damn the girlfriends..lol jk jk

 

dont' feel bad bro... i'm running 235's all around and I only get 21mpg avg.