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Old 08-15-2019, 10:44 AM   #8251
Norm Peterson
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Quote:
Originally Posted by SquatchHunter View Post
Titan 7 T-S5's 18x9.5 +40
Firestone Firehawk Indy 500's 255/35r18
Fortune Auto 500 coilovers and Whiteline LCA's
Car not aligned yet, but there's no rubbing so far.
Tires are stretched more than I'd like but 265's will require fender work.

The tire being stretched is not the problem. 255/35's are measured on 9" (and are recommended out to 10"). The amount of stretch relative to measuring width being "unstretched" is minimal.

It's a flange contour that appears to be providing a false flange well outside where the tire sidewall ends up being based on the real flange contour and bead seat dimensions. This is strictly for visual effect, fooling the observer into thinking the tire is stretched more than it really is.


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Old 08-16-2019, 10:50 PM   #8252
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Another couple of questions on the back of the discussion I started in the last page - putting aside differences in fitment in terms of aesthetics, is there an objectively better option between 18x9.5 +38 and 18x9 +35 for this car from a functionality/driving performance perspective?

Would the higher offset but wider width with the 18x9.5 +38 be more in keeping with manufacturer specs as opposed to the lower offset but closer-to-OE width of the 18x9 +35?
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Old 08-17-2019, 10:38 AM   #8253
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OEM is 18x8.5 with a 55 offset.

Assuming that only the wheel width matters to keep the same backspacing to avoid rubbing on suspension the 18x9.5 would require a 43 offset. 45 is safe. No way the stock clearance is less than 2mm.

The 18x9.0 would require a 48 offset. 50 is safe.


To keep it as close to OEM as possible you should stick with no less than a 45 to 50 mm offset.

Tire rack shows a wheel 18x9 with a 55 offset for the WRX. So the OEM 55 mm offset is OK with at least some wheels even with a 9 inch width. This implies the stock inside clearance is more than 7mm.

The +38 offset is closer than the +35 to OEM, but not enough to matter. Wheel width does not affect scrub radius, only offset does. Change in scrub radius will affect handling during hard stopping, heavy acceleration and hard turns. Wider wheel width affects handling similar to tire width, and will improve handling on dry roads, and slightly decrease handling on wet.
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Old 08-17-2019, 08:40 PM   #8254
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Quote:
Originally Posted by MountainMan10 View Post
OEM is 18x8.5 with a 55 offset.
OEM for my 2015 WRX is 17x8 +55. I'm not sure whether or not that's specific to the AUDM, but according to fastwrx.com's wheel information page there are indeed two specs which could by why we're both thinking of different OEM specs: 18x8.5 +55 with 245/40R18 and 17x8 +55 with 235/45R17.

Quote:
Originally Posted by MountainMan10 View Post
Assuming that only the wheel width matters to keep the same backspacing to avoid rubbing on suspension the 18x9.5 would require a 43 offset. 45 is safe. No way the stock clearance is less than 2mm.

The 18x9.0 would require a 48 offset. 50 is safe.


To keep it as close to OEM as possible you should stick with no less than a 45 to 50 mm offset.

Tire rack shows a wheel 18x9 with a 55 offset for the WRX. So the OEM 55 mm offset is OK with at least some wheels even with a 9 inch width. This implies the stock inside clearance is more than 7mm.

The +38 offset is closer than the +35 to OEM, but not enough to matter. Wheel width does not affect scrub radius, only offset does. Change in scrub radius will affect handling during hard stopping, heavy acceleration and hard turns. Wider wheel width affects handling similar to tire width, and will improve handling on dry roads, and slightly decrease handling on wet.
I appreciate the explanation, however my question was asking which of the two sizes I listed would be better from a performance perspective. Seems like as with most things there isn't a simple answer to this question.

What I've gathered from your post is that the 18x9.5 +38 is likely a better option as far as keeping geometry closest to OEM spec. Based on what Norm has said previously, the other benefits of the wider wheel would include increased lateral resistance and improved turn-in response.

On the other hand, would the slightly thinner wheel of the 18x9 +35 in theory reduce rolling resistance and thus have less of a detrimental effect on straight-line performance (i.e. the thinner wheel/tyre will affect acceleration less) as well as fuel economy (not something I'm concerned about)?

Coming back to fitment, the 18x9 +35 would be the safer option as the outer edge of the wheel will poke out less than the 18x9.5 +38.

Last edited by rst.ack; 08-17-2019 at 08:59 PM.
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Old 08-17-2019, 10:13 PM   #8255
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Quote:
Originally Posted by rst.ack View Post

Coming back to fitment, the 18x9 +35 would be the safer option as the outer edge of the wheel will poke out less than the 18x9.5 +38.
Yes but only by 3mm so very minimal difference.
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Old 08-17-2019, 10:23 PM   #8256
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Originally Posted by dpetro1 View Post
Yes but only by 3mm so very minimal difference.
Yes it's small but it could be the difference between rubbing and not.
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Old 08-18-2019, 07:37 AM   #8257
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Quote:
Originally Posted by rst.ack View Post
OEM for my 2015 WRX is 17x8 +55.
Oops, I quoted the spec for my STI, not your WRX. But the that doesn't change anything in my answer. The +55 is the most significant number.

Quote:
Originally Posted by rst.ack View Post
Yes it's small but it could be the difference between rubbing and not.
Actually a 9.5 inch wheel with the same offset as a 9 inch pokes out 6 mm farther. So actually the 9.5 +38 pokes out 3mm more than the 9 +35. It is the tire that will rub. The shape of the tire on a 9 vs 9.5 could vary by more than the 3mm.

Both your choices are very close in all aspects, both performance and fit. They are both at the limit of what will fit without rubbing. It may come down to actual tire chosen to determine if it rubs.

Last edited by MountainMan10; 08-18-2019 at 07:48 AM.
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Old 08-18-2019, 09:34 AM   #8258
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Quote:
Originally Posted by MountainMan10 View Post
Tire rack shows a wheel 18x9 with a 55 offset for the WRX. So the OEM 55 mm offset is OK with at least some wheels even with a 9 inch width. This implies the stock inside clearance is more than 7mm.
A really crude measurement of the clearance between the inner wheel flange and the strut on my '19 WRX shows about 19 mm clearance there (that being the OD of the 1/2" socket that I could slip through that space).

From that, you should be able to go all the way to the OE +55 offset with 18x9.5 wheels before strut rubbing even starts to be a concern.


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Old 08-18-2019, 10:10 AM   #8259
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And yet the RPF1s dont come in 18x9.5 +55 The closest I can get is 18x9.5 +45 but they only come in silver and I'm after flat black wheels...

The next best are Rota DPT in 18x9.5 +44 but I can't determine the concavity of that width/offset nor can I find how much extra weight the cast wheels carry over the flow-formed RPF1s (plus I just prefer the looks of the RPF1s).
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Old 08-18-2019, 01:11 PM   #8260
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I have the DPT's on my 15 WRX.
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Old 08-18-2019, 05:01 PM   #8261
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I have the DPT's on my 15 WRX.
Nice! Specs?
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Old 08-18-2019, 05:14 PM   #8262
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18x9.5 +44 hyper black with 255/40 Generals. I like them. I am hoping to lower a bit with coilovers but not sure how easy it will be.
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Old 08-18-2019, 06:01 PM   #8263
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The 255/40 looks good. I think I'm going to do that on my next set.
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Old 08-20-2019, 11:03 AM   #8264
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Quote:
Originally Posted by rst.ack View Post
And yet the RPF1s dont come in 18x9.5 +55 The closest I can get is 18x9.5 +45 but they only come in silver and I'm after flat black wheels...

The next best are Rota DPT in 18x9.5 +44 but I can't determine the concavity of that width/offset nor can I find how much extra weight the cast wheels carry over the flow-formed RPF1s (plus I just prefer the looks of the RPF1s).
Have you considered having them powder coated or painted? I was looking at some used wheels and they dealer I was talking with quoted about $600 to have the wheels powder coated. I know it is an extra cost but if it's within your budget you should ask around and see how much it would cost.
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Old 08-23-2019, 03:18 AM   #8265
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Quote:
Originally Posted by MountainMan10 View Post
Have you considered having them powder coated or painted? I was looking at some used wheels and they dealer I was talking with quoted about $600 to have the wheels powder coated. I know it is an extra cost but if it's within your budget you should ask around and see how much it would cost.
Haven't considered powdercoating, and I'm not too keen on adding $600 to an already expensive (>$2k) mod
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Old 08-27-2019, 04:45 PM   #8266
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Quote:
Originally Posted by rst.ack View Post
Thanks for posting, pretty much confirms that the setup I proposed will work great. Clean ride!

You said old setup -- what's your new/current setup?


advan tc3 18x10 +25, 265/35/18




Last edited by kaeknows; 09-01-2019 at 08:45 PM.
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Old 09-04-2019, 08:04 PM   #8267
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Default Updated: 275/30R19 with 19x9.0 BBS/RCF Wheel.

Here is my 2015 STi with 275s.

Tire: Michelin Pilot Sport A/S 3+
Size: 275/30ZR19
6-Rib Tread Design
Serv. Desc: 96Y
UTQG: 500 AA A

Wheel: Lexus / BBS RC-F 19x9.0 +50mm.







Stock Suspension, No fender roll / No rub even with All the Passenger and Cargo.
About Three finger space between tire and Stock suspension. So close and Clears.

Thank you.

Last edited by evei0326; 09-12-2019 at 05:55 PM. Reason: Photo not displaying imgur
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Old 09-05-2019, 07:21 AM   #8268
Norm Peterson
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Quote:
Originally Posted by evei0326 View Post
Here is my 2015 STi with 275s.

275/30R19 with 19x9.0 +50mm.







Thank you.
Pictures still not working.

Imgur can't find them for me when I go to your imgur.com/xxxxxxx address directly, either.


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Old 09-05-2019, 04:49 PM   #8269
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Default Trying Again With Flickr

Please Delete this post.

I think I have fix.

Last edited by evei0326; 09-05-2019 at 04:57 PM. Reason: Photo did not load.
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Old 09-09-2019, 01:19 PM   #8270
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I've been trying to nail down a definitive answer, but I keep getting conflicting information. I mounted a set of 18x9 +35 wheels, wrapped in 255/40s. I'm personally getting a bit of rub in the rear when I have weight in the back. It seems to be that little plastic hump on the underside of the rear arches. Aside from that, no other contact. All of this is on stock suspension

I've seen others say that they've fit my size, around my size, or even my size with bigger tires and zero modification. I've also seen, and been told, that rolling fenders is necessary. At this point I'm just confused, and wondering if there's anything I can do (not really a fan of rolling fenders) to get those wheels to work without rub. I've been thinking about a 255/35 to give myself a little extra clearance as well; but, any help that anybody can give me would be greatly appreciated.
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Old 09-09-2019, 08:50 PM   #8271
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What suspension are you on? Maybe the stock 245/40 would clear up your issue?
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Old 09-09-2019, 09:28 PM   #8272
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Quote:
Originally Posted by evei0326 View Post
Here is my 2015 STi with 275s.

Tire: Michelin Pilot Sport A/S 3+
Size: 275/35ZR19
6-Rib Tread Design
Serv. Desc: 96Y
UTQG: 500 AA A

Wheel: Lexus / BBS RC-F 19x9.0 +50mm.

Beautiful! That's a great set up and it looks great with the stock suspension!

Do you have any shots from directly behind or head on?
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Old 09-10-2019, 09:40 AM   #8273
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Quote:
Originally Posted by dpetro1 View Post
What suspension are you on? Maybe the stock 245/40 would clear up your issue?
As far as I know, stock. I bought the car used, and it had a few mods on it, but the suspension didn't seem to be one of them. Would it be better to go 245/40, 255/35, or 245/35?

I'll take a picture later to show where on the tire it's making contact. Also try to check it the springs look like they are non-oem.

Also not sure if this helps to determine, but this is how it sat on the stock wheels.

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Old 09-11-2019, 10:40 PM   #8274
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Originally Posted by disillusions View Post
As far as I know, stock. I bought the car used, and it had a few mods on it, but the suspension didn't seem to be one of them. Would it be better to go 245/40, 255/35, or 245/35?



I'll take a picture later to show where on the tire it's making contact. Also try to check it the springs look like they are non-oem.



Also not sure if this helps to determine, but this is how it sat on the stock wheels.



Car definitely looks a little low. I would be really surprised if you were getting any rubbing at stock height.

As for tires, going to a 35 series is going to be under sized from stock. I would try to stick to 245/40 if you can.
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Old 09-12-2019, 04:44 PM   #8275
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Quote:
Originally Posted by dpetro1 View Post
Car definitely looks a little low. I would be really surprised if you were getting any rubbing at stock height.

As for tires, going to a 35 series is going to be under sized from stock. I would try to stick to 245/40 if you can.

I'm going to have to check the suspension this weekend to see if any lowering springs were installed, or if they're just shot in general.

Also, this is how it sits with the wheels on:

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