18x9.5 +12

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Craig Burriss

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Hey guys,
My new wheels just arrived. 18x9.5 with a +12 offset, which equals about a 5.75” back space.
I had been looking for some in this exact size and these popped up, brand new never mounted on anything, they’re MST wheels... the same eBay brand I’ve had on a few other cars. They have always held up, even with the abuse I’ve put them through (Auto cross, aluminum ladders on I-85, pot holes, catching air).
The hub bore is 73mm, which I thought would work, but the front hub of my Duster with 73+ disc brakes stick out 2-3 inches, which would go through the face of the wheel. There’s a 5mm lip in the wheel bore that holds the center cap that’s going to have to be removed.
They fit on the back with about 1/2” of clearance between the lip and the stock location leaf spring, so they would fit with a little tire stretch. But I’m in the process of building a four link, so I’m going to have 285/35r18s on all four corners.
It looks like the front wheel will have plenty of room between the upper ball joint and the tie rod end. My front fenders are already pretty hacked up, so there’s no clearance issue there. The only thing I can see that might cause an issue is when the tire is mounted, it might hit the frame at full steering lock, and will be pretty close to the brake line bracket.
Regardless of what the tire hits, I’m going to make them fit, because I love the way they look.
Keep in mind the front wheels are going to be about 5/8” further inward.
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After taking my wheels to the campus machine shop and boring the center hole out a smidge, they fit perfectly! The wheel doesn’t hit anything anywhere during suspension travel or steering movement. The only thing that might touch is the tire and the frame rail.
4 285/35r18 tires coming as soon as my Miata sells.
I have PerformanceOnline UCAs
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I really don't think those front wheels are gonna work out for you with a 285/40/18 on there. In your bottom picture in your first post the outer lip of the rim is well outside the fender lip. In the last one above, remember you'll have 4" of tire above the lip of that rim.

The tires will touch the frame as well. Most of that is the QA1 LCA's don't have steering stops on them like the factory LCA's do to limit the steering angle, you're getting more steering angle than a car with a factory LCA.

My 18x9's are +35. I lose 5mm to my 13" brakes, so, +30 if you're comparing to a 73+ disk brake track width. Even with 275/35/18's my fenders have had the lips rolled and the fender itself pushed out with the lip roller to clear the 275's at the ride height I run. Those 285's will be almost a full 1" further out than my 275's are. They're taller too.

My car sits low and all, but there isn't an extra inch there unless you go higher than factory ride height. And keep in mind the clearance I have is aided by rolling the lip flat, pushing the bottom of the fender corner out almost 2", and pushing the middle of the fender out with the roller. If you look at the bottom two pictures especially you can see my fenders have a convex curve to them where the factory had them flat.

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This isn't even full steering lock in the front. It clears on mine, but not pushed out another inch.
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The "Project Yankee" speedhunters car did something similar. They ran 17x9's with a -10 offset. But only a 255/40/17, which is only a 25" tall tire. Now, that tire sits 1.4" outside mine. But you can see on that car, even with a heavy negative camber and a pretty short tire, they completely hammered the fender to get clearance. The body line is totally trashed, and the indent around the wheel opening is completely rolled flat and reversed. And I would bet that tire still rubs on that fender in all kinds of normal street driving situations.

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They probably should have just added flares to this car to match the JDM style they were after. What's really funny is that they could have easily fit those wheels up front if they'd just used the proper offset.
 
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I have the same brakes and offset wheels as 72bluNblu, 18x9 +35 and the Dr Diff 13" brakes. 275-35-18 Continental ExtremeContact DW Its absolutely the furthest out you can push the wheels and get away with it. I have the front brackets for the fenders pushed all the way out and I had to replace the fender bolts in the back of the wheelwell with pan heads because they rubbed on the tire while turning.
 
I really don't think those front wheels are gonna work out for you with a 285/40/18 on there. In your bottom picture in your first post the outer lip of the rim is well outside the fender lip. In the last one above, remember you'll have 4" of tire above the lip of that rim.

The tires will touch the frame as well. Most of that is the QA1 LCA's don't have steering stops on them like the factory LCA's do to limit the steering angle, you're getting more steering angle than a car with a factory LCA.

My 18x9's are +35. I lose 5mm to my 13" brakes, so, +30 if you're comparing to a 73+ disk brake track width. Even with 275/35/18's my fenders have had the lips rolled and the fender itself pushed out with the lip roller to clear the 275's at the ride height I run. Those 285's will be almost a full 1" further out than my 275's are. They're taller too.

My car sits low and all, but there isn't an extra inch there unless you go higher than factory ride height. And keep in mind the clearance I have is aided by rolling the lip flat, pushing the bottom of the fender corner out almost 2", and pushing the middle of the fender out with the roller. If you look at the bottom two pictures especially you can see my fenders have a convex curve to them where the factory had them flat.

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This isn't even full steering lock in the front. It clears on mine, but not pushed out another inch.
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That first post was before I bored the center hole out. So the wheel actually sits up against the hub now, an inch further in than that last picture of the first post. The 285/35 is the exact same height and top of the tire will be about 5/8” further out than my current setup.
As seen in this picture here.
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The lower corners of my fenders are rusted and cut up, so I won’t have any issues there. If the top of the fender hits, I’ll roll and push them as much as needed.
You can see the hacky fender corners here. (This was before they fit the hub)
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And because the fenders are already like this, I’m not worried about damaging them, or modifying them.

Your car is amazing and it’s awesome you got 275s under the front with such slight modifications.
 
American Racing, IIRC they are torque thrust M's. You will have to get the center holes machined. The center caps are rocket racing and they had to make some machining for the fit for those also. The center caps that come with it won't work.
Thanks, they look good on your car. I would definitely have to do some fabbing on the hub bores because of my Wilwood brakes.
 
Miata sold so I just ordered 4 285/35 tires. I was going to get some nice soft Toyos or Nittos, but I figured since there’s a chance these will rub somewhere and get damaged, I’ll start off with some cheaper tires. A friend at the local tire shop hooked me up with an insane deal on some new Falken fk510s. They claim they’re a summer tire, but they look like an all season from what I’ve seen. But for the price, I’ve got nothing to lose. Since so many events are getting canceled, it’s not like I need a softer tire right now anyway.
Getting them mounted on Thursday, so I’ll post pictures when I get them on the car.
 
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Miata sold so I just ordered 4 285/35 tires. I was going to get some nice soft Toyos or Nittos, but I figured since there’s a chance these will rub somewhere and get damaged, I’ll start off with some cheaper tires. A friend at the local tire shop hooked me up with an insane deal on some new Falken fk510s. They claim they’re a summer tire, but they look like an all season from what I’ve seen. But for the price, I’ve got nothing to lose. Since so many events are getting canceled, it’s not like a need a softer tire right now any way.
Getting them mounted on Thursday, so I’ll post pictures when I get them on the car.

Sounds like a solid plan to me!
 
Super busy today, but I couldn’t resist bolting one on and playing around with it.
I removed the torsion bar adjuster and let the car sit in the LCA bump stop while I turned the wheel. It BARELY hits the fender lip. I’ve borrowed a fender roller and have a plan if that’s not enough.
If it’s not raining all weekend I’ll update again then.
This picture is before I lowered the car all the way down
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I don't know how you plan to run it, but my bump stops are cut down, so it can ride low and also have suspension travel.

My opinion is that you need about an index finger width of room at all the worst case conditions when its sitting in one spot for it not to rub at all. Between tire deflection, suspension deflection due to bushings and everything else, it tends to move around a little bit. Mine has brushed a few times if you take a turn at speed and then hit a bump while doing it. Nothing serious though.
 
Super busy today, but I couldn’t resist bolting one on and playing around with it.
I removed the torsion bar adjuster and let the car sit in the LCA bump stop while I turned the wheel. It BARELY hits the fender lip. I’ve borrowed a fender roller and have a plan if that’s not enough.
If it’s not raining all weekend I’ll update again then.
This picture is before I lowered the car all the way down
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Good grief!

I can't believe that fits that well, even with the corners of the fender opening cut back. You're sure that's a +12?

The top of the fender is a piece of cake. You can roll that lip and use the roller to push the fender out a good 1/2" without any trouble. Just need one of these bad boys
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Summit Racing SUM-900790 Summit Racing® Fender Rollers | Summit Racing
 
I have pondered cutting the frame where the tire hits at full lock and plating it, essentially notching the frame in a lateral sense vs a vertical (as you would "C" notch the rear frame if lowering the vehicle running bags or something that you see all the time with low riders.)
 
Good grief!

I can't believe that fits that well, even with the corners of the fender opening cut back. You're sure that's a +12?

The top of the fender is a piece of cake. You can roll that lip and use the roller to push the fender out a good 1/2" without any trouble. Just need one of these bad boys
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Summit Racing SUM-900790 Summit Racing® Fender Rollers | Summit Racing
Yes it’s a +12, are the tops of the fender arches different on your Demon/Dart fenders than my regular Duster fenders?
That’s the exact roller I borrowed, I played around with it for a few minutes. Seems to work a lot better than a hammer or the “baseball bat” method.
 
I have pondered cutting the frame where the tire hits at full lock and plating it, essentially notching the frame in a lateral sense vs a vertical (as you would "C" notch the rear frame if lowering the vehicle running bags or something that you see all the time with low riders.)
These don’t hit the frame at full lock, and I have slightly more steering angle than factory LCAs, I could’ve gone wider and probably fit a 305 if I had a half inch less back spacing on a 10” wide wheel.
Maybe next time
This is basically full steering lock
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I don't know how you plan to run it, but my bump stops are cut down, so it can ride low and also have suspension travel.

My opinion is that you need about an index finger width of room at all the worst case conditions when its sitting in one spot for it not to rub at all. Between tire deflection, suspension deflection due to bushings and everything else, it tends to move around a little bit. Mine has brushed a few times if you take a turn at speed and then hit a bump while doing it. Nothing serious though.
I haven’t decided a ride height yet, but I’m going to figure that out soon when I build my 4-link. The front ride height will probably be a little lower than pictured above. The rear will be about 4” lower.
 
Is this car gonna put time in on the street?
Where is your SAI gonna end up, and
what alignment specs are you gonna target?
For a street car, getting them on there is only a part of the challenge; after all that, you still have to drive it , steer it, and brake it.

I mean I'm all for it, cuz it looks great.
 
Is this car gonna put time in on the street?
Where is your SAI gonna end up, and
what alignment specs are you gonna target?
For a street car, getting them on there is only a part of the challenge; after all that, you still have to drive it , steer it, and brake it.

I mean I'm all for it, cuz it looks great.
This car is 99% street driven. The alignment is kind of all of the place right now, and if I’m being honest I had to google what SAI meant lol. I’m going to try to have the camber as minimal as possible, but wouldn’t mind a degree or two in the negative direction if that’s what it takes, and I usually set my toe with a measuring tape to where the fronts of the tires are about 1/16” closer together than the rears. Just whatever the best combination of, tires not hitting the fender, not wearing out prematurely, and handling good on the street.
I’m just learning and making it up as I go.
 
Yes it’s a +12, are the tops of the fender arches different on your Demon/Dart fenders than my regular Duster fenders?
That’s the exact roller I borrowed, I played around with it for a few minutes. Seems to work a lot better than a hammer or the “baseball bat” method.

That's crazy! But if it works it works! Mine are +30 compared to stock 73+ disks, so, that's 18mm further out on the rim, plus the extra tire width from the 285.

As for the Duster vs Dart/Demon fenders, I don't think so. I have actually run my 18x9's with 275/35/18's with both my Duster and my Demon fenders. The Duster fenders were more limiting at the rear corner of the fender opening though, so I was more concerned with that than I was with the top of the fender. The heights of the opening are the same. The Duster fenders do have that little factory flare to the lip, but I don't think it adds much if anything. To be honest, the bigger clearance issues I've had have been at the front corner of the opening.

The only thing is that my Duster sat a little higher when it had the Duster front end, since I've been running the Demon front end I have lowered it some which has necessitated the fender lip roll. Initially I went from Duster fenders to Demon fenders with no rolling, and only the treatment on the lower front corner with the extended fender brace and lip trim.

I'll be interested to see if any minor rubs come up on the street. The only place mine ever hit now are the rear of the frame at full steering lock, they just kiss the frame there with the lack of steering stops on my QA1 LCA's. I did get a couple of squeaks on the body after I lowered it a bit more before I rolled and pushed the fenders.

Here's the same wheel combo on with the Duster fenders, you can see the clearance compared to the pictures above with the Dart fenders. Not 100% fair because I did push the fenders when I rolled the lips on the Dart fenders.

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I'm still perplexed how you fit that much tire under there. I have to find someone who has a fender roller or buy one for myself. I'm scratching my head how I'm going to get 265/35/R18's under my Dart.
 
Another busy day, but I bolted one on the rear, it fits better than I was expecting. I thought it wasn’t going to even bolt on because of the leaf spring, but it barely fits on there with about a paper thickness a clearance. I was already planning on getting some spacers to even out the front and rear track widths. It looks stupid right now because the rear sits so high and they’re sank into the well so far. Just making want to get started on my 4-link even more.
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After rolling the fender as flat as I could, the tire now clears pretty good at the ride height I plan on running. But when I set the suspension on the bump stops, it starts to hit the fender as the steering is approaching full lock.
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Keep in mind, this is not the final product. It started raining before I could finish the one side I’ve been working on, but it’s to a point now where it would probably never rub. I just used some random hardware I had laying around to see if this would even work. And it does!
I attached a turnbuckle to the unrolled part of the fender and the inner fender piece. This allowed me to loosen the turnbuckle until the fender was pushed out just enough.
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Every picture was taken with the suspension resting on the LCA bump stops. Once I add another turnbuckle to the front side of the wheel well, I don’t see it ever rubbing anywhere.
I may not even need the other turnbuckle, so I’m going to wait until I drive it with this setup before I drill anymore holes.
 
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