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FAQ: Offsets, Sizes for Rims and Tires on the GT! Xenonk Version! - Vol 2


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From Xenonk's previous thread.


I finally compiled the most completed info I can come up with for wheel and tire fitment questions that everyone has. I mapped this entire post out so that you can pick a rim size you want and the rest will follow, including tire size.. I worked out this post so that you guys can decide on a tire size and it will point to you of what rim specs you need to fit onto the car.. as for brands and types of wheels and tires, well, that's a totally different thread on its own.


-GT's bolt pattern is 5x100mm, NOT 5x114.3. Only the 2005+ Impreza WRX STi is currently running 5x114.3mm. Stock GT wheel is 17"x7" +55mm (still need full verification if it's different from model years), but it's been confirmed for 05' rims on post #1522


-OBXT bolt pattern is 5x100mm with +48mm offset (weighing around 20.5 lbs per rim). OBXT wheel is 17"x7".


-2.5i and 3.0R models will need confirmation on stock rim sizes.


-Center bore must have to be 56mm or larger (if the bore is larger than 56mm, use hub centric rings to fit properly to your wheel's center bore, but not always necessary if you have wheels with conical lugnut seating, the wheel will eventually center itself, but that's your call of how you want to go about that).


-SpecB, OBXT, and 3.0Rs can use shorter tire sizes from the GT. But be sure to check and compare the load capacity of the tires. Try to use the same tire load capacities if you can within +/- 100 lbs. You can certainly always go over, but not under (as this requires for you to run higher tire pressures and this could cause more of an issue for tire wear).


-Lug nuts threading are 12mmx1.25mm. Open or Closed End lugs will depend on the mounting thickness of your rim, usually, closed ends (like the stock ones) are fine.


-Here we go, here are your choices for rim widths (regardless of it being 17", 18", 19" or 20" rims):


{offset in BOLD are the closest possible offset to OEM's scrub radius, you'll notice that once you go past 8" wide rims, you will run out of room on the inboard side to put/stuff any more of the wheel/tire to maintain the OEM scrub radius.. 8" and up will increase positive scrub radius}


6.5" (+34mm to +60mm offset, +55) *for 2.5i only

7.0" (+37mm to +57mm offset, +55)

7.5" (+40mm to +54mm offset, +55)

8.0" (+43mm to +51mm offset, +53)

8.5" (+45mm to +48mm offset, +45) *will need to roll the fenders if tires are wider than 255

9.0" (+43mm to +45mm offset, +43) *will need to roll the fenders if tires are wider than 255

9.5" (+38mm to +40mm offset, +38) *will need to roll the fenders if tires are wider than 255


and it also depends on what kind and size of tire you want to run as well (and that can get messy). But to be on the safe side, here is the tire widths you can put on each rim:


195mm = 6.5", 7" and 7.5"

205mm = 6.5", 7" and 7.5"

215mm = 6.5", 7", 7.5" and 8"

225mm = 7", 7.5", and 8"

235mm = 8", 8.5", and 9"

245mm = 8", 8.5", and 9"

255mm = 8.5", 9", and 9.5"

265mm = 8.5", 9", and 9.5"

275mm = 9" and 9.5"

285mm = 9" and 9.5"


Once you decide on the rim size, the tire width you want to run, here are your final tire choices. Note that not all tires are built the same way, so sometimes you'll find two different tire models with the same size (225/45/17), but one can fit on a 7" rim, while the other one will need a 7.5". You'll have to look around the manufacturers' specs on sectional width of the tire.. normally you want your rim width be no more than 1.5" less than the tire's sectional width. For example, if you have a 8" wide rim, your tire's sectional width shouldn't be more than 9.5" or you'll have to deal with the flex on the tire sidewalls. Most performance driving set ups are 1" difference (ie. a 8" wide rim with 9" wide tire). Below I listed for you by rim diameter of which I recommend running with some notes on each tire with notes to go along with them as well:


16 in. rims (for 2.5i, 2005-on) only:


195/60/16 (great for snow rally or snow use)

205/55/16 (OEM sizing which is also good for some non-tarmac surfaces)

215/55/16 (oversized for the rim protection, but very sloppy sidewall handling)

215/50/16 (wider footprint used for more daily driving without harsh gas consumption)

225/50/16 (great for autocrossing, still usable for daily driving all year round)



17 in. rims (for GTs 2005-on):


205/40/17 (only for SUPER FAST acceleration and torque; for autocrossing only, do not use for daily driving)

205/45/17 (only for FAST acceleration and torque; for autocrossing only , do not use for daily driving)

205/50/17 (good for snow rally)

215/45/17 (stock)

225/45/17 (good autocross performance tire size for gearing, more mph per gear)

235/40/17 (good autocross performance tire size for torque, more acceleration)

235/45/17 (tallest tire you could use under the GT due to possible suspension clearance issues, best used with an 8" wide wheel)

245/40/17 (good autocross performance tire size for traction, will need to have a flatter alignment to make use of the grip)

255/40/17 (maximum grip, good for track days, will need a 9" rim to make use of the contact patch and a good alignment as well).


18 in. rims (for GT 2005-on):


215/35/18 (only good for autocrossing use, do not use for daily driving)

225/35/18 (only good for autocrossing use, do not use for daily driving)

215/40/18 (uncommon tire size, close to OEM overall tire diameter, good for daily driving)

225/40/18 (typical sizing, most popular size, GREAT for daily driving)

235/40/18 (very large, but great for pot-hole city driving, may need fender rolling)

235/35/18 (rare size, but closest to OE tire sizing to keep the spedometer reading correctly)

245/35/18 (common autocross, performance size, very good for daily driving)

255/35/18 (very good daily driving size, even better on the track)

265/35/18 (very good daily driving use, but the car wont be able to use all 265mm of tread for the track)

275/30/18 (tallest tire you can mount without fender clearing issues on a 2" lowered car if you get the right offset)

285/30/18 (aka, the "STREETS OF DREAM" setup... the widest you can go.. this is the next tire size I am going for and a rim to match it)


18 in. rims (for Spec B.2006-on, 3.0Rs 2008-on):


225/40/18 (common tire to use and gives a better acceleration since it's 0.5" shorter)

235/40/18 (rare size to find, but near stock height for proper gearing)

245/40/18 (popular tire size for the larger cars)


19 in. rims (for GT 2005-on):


225/35/19 (common typical sizing for 19" for our cars)

235/35/19 (tallest tire you can mount without fender clearing issues on a 2" lowered car if you get the right offset)

245/30/19 (rare size, but also tallest tire you can mount without fender clearing issues on a 2" lowered car)


Use these at your own risk, but to my knowledge on a lowered car with a small-spring perch type coilover, it should work and ride fine. The most you'll probably have to do to the fenders is to just roll the lip of it in to give yourself another 5mm of clearance. I hope this helps.

Previous version is found here Edited by SBT
Added post 1 from previous thread
- Pro amore Dei et patriam et populum -
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decided on a 255/35 18 sumitomo htr z III for my 18x8.5 +45s. returned the 18x8 +35 because i want to run a fat tire. Wedssports coming soon. I wont need any fender mods i dont think since im already running a 225/40 on 18x8.5 +38s.


And theyll clear brembos without a spacer. psyched to see what it will look like.

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current tire is a/s 225/40 on +38s, new tire uhps 255/35 on +45s.

FA 510s with 8k 6k swift and radial bearings with camber plates on the coils

fenders are already rolled, no pull. if i need to pull nbd im not overly concerned.

im not a fan of slammed cars anyway so if i need to raise it up it doesn't really matter to me, id much rather a large tire.

right now car is on s-techs but coils are being built and shipped and here in about a month. 8-12 weeks for the SA10R blc to come from Japan


lose 7mm on the poke, but gain 15mm on the tire on the outside (i think), so effectively +8mm on the outer edge, but the 35 sidewall is a bit less tall, so I am thinking ill be OK.

if i need to run a bit of camber thats fine as well.

Edited by stocklgt
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  • 3 weeks later...

Hi everyone.

I am absolute amateur talking about wheel tire fitment, therefore I'm looking for you advice.

My Legacy 2010 2.5 is fitted with the stock 16" 5x100, but I want to go bigger.


I particularly like to have the new wheels flush mounted with the car body. Therefore I looking for a lower offset.

What I like are few models from AVID1 - AV20 and AV30 and XXR 530 and 550.




If I go for AVID1 AV20 - they come in 17x8 +35, 18x8.5 +33 and 18x9.5 +38.

The different offset value is making it more complicated for me to decide. I don't want to modify anything in the car - no lowering, no rolling the fenders - just to upgrade with a new set of flushed wheels.


Can you please comment on what option would be best for me and what tire size I should look for?

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The newer legacies can fit 18x9.5 +38 easier than the 05-09. Id go with the 9.5 setup. If you dont plan on dropping the car you should be able to pull it off with little to no roll. what tires do you plan on running
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stocklgt, I have no idea which tire sizes will fit best with the different wheels sizes I mentioned in my previous post. Any recommendations will be highly appreciable.

What I really don't want to do is to roll the fenders. The safest way is to go for 17". But what if I go for 18"?


I really like how the AV-20s sit and how the tires are giving some curb protection as well. This is 18x8.5 +33 and 245/40/18 tires combo. The only problem is that I don't know how they fit on my Legacy


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  • 4 weeks later...
Looking for some input.. I couldn't resist picking up a nice set of 18x8 enki wheels today...I was initially planning on putting them on my bmw(which is what they came from), but I think the spec b would be better for them. So my problem is they are 5x120 with an inset of 42. I see I can get lug adapters that are 15mm thick, so will those along with the 42 inset cause an issue running 225/40/18 tires?
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It will now effectively be a +27 offset. I ran 18x8.5 +38 on 225/40 and had to roll on s-techs. 18x8 +35s poke a little, depending on how low the car is you will need to roll and a possible pull. If it were me i'd stay far far away and look for a set that will fit better and fit properly. make sure to reference this thread before you buy anything you will regret -


Personally I don't like the whole idea of changing the bolt pattern with spacers, makes me nervous, but if you are set on it go for it. When I was a jeep nut I heard of plenty of people using them when they ran a different rear end, and never heard of any issues with it, but your results may be different. I always kept my stock dana rear end because I never really offroaded too much.

Edited by stocklgt
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  • 2 weeks later...

hello everyone, new to legacys and the forum. came from an outback xt. current car is a 2009 3.0r limited, stock wheels were the 18x7.5 55mm. i just purchased some tarmac 3s in 18x8 48mm. my suspension is completely stock and won't be lowered any time in the future.


i was wondering what size tires would be ideal for my setup. i dont need anything crazy its my daily driver and i consider the car to be pretty slow. i see a lot of people running 225/40 which i cant stand the thought of. way too small and stretched for me.


ideally i would like 245/40 but would settle for 235/40 for better fitment. would either of those work? both diameters would only be within +/- 5mm of stock its just the extra 13mm of poke that concerns me. any suggestions would be super appreciated. thanks!!

Edited by 3.0r413
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  • 3 weeks later...
  • 1 month later...

In the summer I am running a 255/35 on 18x8.5 +45s. Wondering if i will have trouble running a 225/40 blizzak winter tire on an 8.5" +35 winter setup? Ive always heard that in the winter you want a more narrow tire due to contact patch and putting more weight in less area to sink down and bite through. But now i'm concerned that the 225 will be stretched too much and can cause some damage to the unprotected edges of the rim. The rims (Ambit RT6 18x8.5 +35) were super cheap, so im not overly concerned about damage, but wondering if it will just be too much stretch and I should just run the spec b stockers with spacers to clear the front Brembos? NY weather is so hit or miss that they may only see 2-3 good snowfalls, but the rest would be semi-freezing mornings and cold evenings.


I only drive around 75-100 miles a week and the car will be breaking in a new motor so no snow hooning this season, but im still a little concerned.


Option 1 - run the 225/40 on the 8.5" +35 wheel and possibly damage the rim/fender

Option 2 - run the spec b stockers with a spacer in front to clear the brembos



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225/40 on 8.5 +35 should not be an issue since the 255/35s already fit.


1/4" increase wheel width per side, is not going to stretch a 225 much if at all.


225mm = ~8.9" section width and on and 8" is slightly wide. Should be very good.


Mount one up and see how it fits.

- Pro amore Dei et patriam et populum -
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awesome, thanks for the help.

the 255 35s aren't fitted yet, still need to get the motor in and put on the coils, but that is the plan. meanwhile ill roll around on stock suspension with the winter setup and get everything dialed in springtime.


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Just looking to run a wider tire on the stock 17" 2005-2009. Stock size is 205/50/17...found post that says I can run 215/45, 225/45. Can I run a 225/50/17? Looking to improve ride quality running the old JDM Bilsteins rev A.


I'm pretty sure I've read a 215/50/17 will fit, but a 225/50/17 will rub somewhere, maybe the strut perch. If you have JDM bils it could be different though.

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