Unfortunately in my haste to get them on ( I swapped them out while home from work on lunch break) I did not weigh them even though I was interested in those numbers. I got the tires and wheels ready to install so no separate weights were possible.

I only turned over 1000 miles yesterday. I have only put gas in about four times now. The first check was the day after I got it. I got 29.4 stock in mostly rural highway driving with some city miles included having driven 186 miles or so. I will say that every time I have calculated the mileage and compared to the trip computer. the calculated number was slightly better than the trip computer average. I know the tank when I filled up that was partly on stock tires and partly 19's calculated to 26.5 and the computer showed 25.2 average. That was 100% city driving and playing a lot. The last fill up was the first completely on 19's and for whatever reason (in a hurry and at a gas station other than my usual) I failed to get it full. I did not even notice until the next day that I only had 3/4 tank of gas. I guess it clicked off early and I did not notice. So no valid check available yet.

I don't see how exactly. The speedometer and the odometer are both slightly off. It is complicated to calculate your actual mileage with this situation.

You can see it through this.
5280 ft/mile = 63,360 in/mile
Stock 16's are 78.1" in circumference
235/35/19's are 80" in circumference

When the stock tires turn 811.2676 times the odometer indicates 1 mile. (assuming the calibration is correct from the factory)
when the 19's are on and the odometer indicates one mile (811.2676 revolutions) you have really gone 64,901.408 inches or 1.0243 miles.
So lets say, for simplicity, your odometer indicates you drove 300 miles on a tank of gas. In reality with the 19's you traveled 307.2983 miles (300 x 1.0243).
Again for simplicity, lets say you used 10 gallons of gas. The car would indicate you drove 300 miles on ten gallons for 30 miles per gallon. In reality you drove 307.3 miles for 30.7 miles per gallon.
That means you could be nearly 1 mpg lower than reality on a tank of gas when calculating the mileage with 19's installed. Not a lot, but low nevertheless.

I guess that could be considered another advantage to running larger diameter tires. When I show 50,000 miles on my car with the 19's installed, I will have really driven 51,215 miles.

And my apologies to tCtuNeR216 for my part in this partial thread jack.
Congrats on the new xB. :D

 

I was thinking that you could take the average speed shown, and extrapolate that out to the correct mileage based upon the average speed in relationship to the known difference.

In other words, if you are within a mpg at 30 MPG, you are pretty doggone close and unless you drive the exact same route each time, with the exact same weather conditions each time, your mileage will probably fluctuate as much as you are calculating the tire size.

Did you measure the tread depth on the tires when new, so that when they wear down you can get an accurate measurement based upon the worn tire diameter ? LOL

 

I would trade my 06 xA for a 08 xB I like the new ones because they arent as boxy.

 

That's a little extreme but you should definitely be factoring in the average Latitude the majority of your miles covered. Otherwise you will fail to account for the variance in the weight of your vehicle caused by the change in gravitational pull at different Latitudes and end up with unexplained variances in your mileage.
I cannot believe you and Fiero failed to examine this factor in your earlier discussion on weights.

 

Soooooo
tCtuNeR216 howz that new xB? :D

 

I just cant resist. I just got off the phone with a Gen 1 owner who changed his 15's to 18's a couple of years ago. I explained the mileage discussion to him & his response was that the 18's did not cause his mileage to go down at all, even with the Gen 1 motor. I would be happy to provide his name and number to anyone who wants independent real world verification of the facts. I will leave this thread alone now, and start my own !

 

I picked up my xb and transfered my wheels over from my previous tc and and the wheels that i ended up going with are 18" sportmax 003 anodized bronze and they weight 17.9 lbs. per wheel thats was a huge difference with the weight from those stock tc wheels.

 

Consider yourself lucky. You are one of the few that can actually use the wheels from your tC on your xB. Not all tC owners have dual drilled 5x100/5x114.3 wheels.

Those 003's are nice looking wheels too. Congrats on the new xB.

 

THANKS
before i had the wheels on my tC it was bronze on white and not many people in this small town like them much
but if you want to check out more pics check out my "myspace"
www.myspace.com\caseyscion
or
www.idahomotorsports.com and i'm caseyscion1