Here's one I like better. Gives you visualized differences:

Tire size calculator

 

Best one

Wheel / tire size calculator / comparer - RIMSnTIRES.com

 

Also, check out the tire & wheel test Car & Driver did linked below if you are considering plus or minus sizing. After reading this I am sticking with oem size wheels for summer tires: 18x8.5 On the S206 Subaru put BBS designed 19-inch x 8 1/2 J forged aluminum wheels (silver)
Michelin Pilot Super Sports 245/35ZR19(93Y) tires

If you plug oem 245/40R18 and 245/35R19 sizes in the tire calculator they come out nearly the same with the 19 just a fraction taller.

Effects of Upsized Wheels and Tires Tested - Tech Dept. - Car and Driver

 

Hi Everyone,

Im trying to go with a an 18x9 wheel for my 2013 sti hatchback.I dont want to make any mods at all. I checked on Rota wheels and their G Force wont fit but the Advan RS Wheel 18x9 5x114.3 is supposed according to the seller. Is this correct from everyone's experience? Anyone have any ideas on brands or models that would work in that 18x9 size?

 

I have just purchased a brand new 2014 Sti hatch in rally blue, yay !
I have a set of ugly Rays Volks Monster just sitting in my garage right now, got them dirt cheap, $200.
I think with the specs, it should fit, but just want to make sure.
17x7.5 et45
17x8 et45
Tire wise, I am thinking 225/50R17.
And also, any recommendations on what tires to get?

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