I was looking at some 17" and 18" wheels (by 7 or 7.5) and wanted to know the best and most affordable tire size recommended for the iQ? I plan on lowering it eventually...but i want them to fill in the wheel gap when I do. (looking to lower anywhere from 1.5"-1.7")

 

Also, the recommended Backspacing for these if you know it too...please and thank you!

 

Tire size for a 17" rim is 205-45-17 the rim should be 17-7 with a 45 offset and 4-100 lug pattern

If you do an 18" your tire size should be a 205-35-18 these tire sizes will keep your speedo working correctly.

 

I recommend 17" dia wheels over anything that can't fit 15"s... the reasons are simple they have more options for less money than any other dia rims. You might find one tire for 16' rims that costs less I did but only one! There are lots of choices in 17" dia wheels and everything in 18"+ will cost more! 17-45-205 are probably as big as you can put on the front maybe 215s but they might rub on tight turns maybe not. The rear you can probably go out to 225s but nothing will be there to catch the spray! = Probably right at the edge of your fenders!
Price check! 215-45-17 start at about $60 and I found 12 under $80! Compare that to 215-45-18 with only two under $100 and all over $80! Vastly more choices at all price points with 17" or 15" compared to any other wheel sizes!
My opinion based on research for a lot of tires on many cars!

PS: I think the offset is 40 for the wheels.
Get a professionals opinion on that not just the guy at the local tire fix it chain store. Call a couple wheel specialists.

 

Correction to my initial post, for a 18" wheel on a Scion IQ the tire size will be a 205-40-18" and the offset will greatly depend on the width of the rim. If you run a 7" wide rim, the offset will be 45, if you run a 7.5 wide wheel you will need to run a 48-50 offset. I am currently running a 18"-7.5" Enkei RSM9 and my offset is a 48mm, I'm on coilovers and my IQ sits low enough to just barely put a finger between the tire and the fender. I probably know more than most what size wheels will or will not properly fit a Scion IQ, I currently own two set of wheels and tires. Both sets of wheels I own are Enkei, one set is 17"-7" 45mm offset, and the other is 18"-7.5" with a 48mm offset. With my current ride height, I do not have clearance issues with either set, but if I was to lower it even a 1/2" more it would begin to rub on dips in the road. I'm very happy with my IQs stance, so I have no desire to lower it any more. If I could figure out how to post pictures of my IQ on the forum using my iPhone or iPad I would do so.

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I didn't have a problem with anyone's post. I was just commenting my opinion freely before I even read the rest of the thread! Those 205s are right on the money for the front I think looking at the pics of BigNuke6's tires! I still think you could get 225s in the rear but again just for looks. It will of course stick to the road better.... but then this really isn't a race car now is it?

 

Keep in mind, unless you have money to throw away, you want to be able to rotate your tires. So putting 205s on all four corners is your best bet, and will still allow you to rotate on a regular basis. The 205s I run a Yokohama S drive will hug the road extremely well and probably far out perform the IQs capabilities.
Your correct, it's no race car, but with the right mods, it sure as heck can handle like one

 

agree, i feel little regret install size 215/35/18 ~~ The best size cant go wrong for 18Inch wheel would be 205/40/18 ..

 

I had 245/60/18's on my xD...its totaled and now have an iQ.

Will the 245/60/18's fit?

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