11-14-2018, 08:26 PM | #1 |
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18" Square Setup - Rotatable
I wanted a setup that I could rotate front to back, but use as much rubber as possible. Here is what I have come up with:
18x10.5 ET40 from Apex (FL5) 305/645/18 Pirelli DH slicks Fronts use a 20mm spacer This clears my strut by about 5mm, tire has 10-15mm clearance. Fits just about perfect.
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11-15-2018, 12:15 PM | #3 |
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Nice! I've been thinking about a second track wheel set and was wondering what the widest square setup possible might be, perhaps this is it! I'm still on OE suspension for now, do you think 10.5's front and back would fit? I can go narrower on the tires for now if I need to.
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11-15-2018, 01:08 PM | #4 |
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11-15-2018, 01:22 PM | #5 |
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In case it might help someone, here is a picture of the inner strut clearance for a 285/645-18 mounted on an 18x10 et25 Apex SM-10, no spacers.
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11-15-2018, 01:30 PM | #6 | |
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11-16-2018, 08:24 PM | #7 |
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Pirellis run small
FYI on the Pirellis. Here is a comparison
18x10.5 with 305x645x18 Pirellis vs Hoosier A7 18x10 with 295x30x18 x2 18x11 with 315x30x18 x2 Hoosiers are big!
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11-19-2018, 03:51 AM | #8 |
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Sorry to go off topic but has anyone ever logged oil pressure when running slicks?
Also, am I right in thinking 18x10 et 25 all round with 265/35/18 would be ok and rotatable on a car without ceramics? Can anyone confirm whether a spacer is required on the front when running M Performance HAS? Thanks |
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11-19-2018, 10:03 AM | #9 |
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I'm 90% sure you will need a spacer with the HAS. Why so narrow on the tires? None of the guys racing the cars, including the GT4 racecar have had issues from what I've heard with oil starvation, but I hear you. I came from the LS V8 world and even with dry sump those motors have issues.
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11-19-2018, 11:04 AM | #10 | |
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Narrow tyres are purely down to cost and availability. It’s good to hear that there aren’t reported problems with race cars on slicks - it’s such a huge step forward in comparison to older cars, same with brakes and cooling. |
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11-19-2018, 11:28 AM | #11 |
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Doubtful. The issue is the MP HAS puts the spring perch below the tire area. Since the 265 will be stretched on the 10" wheel you do have that going for you, but the 18x10et25 only has maybe 5mm to the strut, so anything additional in the area is going to be a an issue. I would just add a 10mm spacer and call it a day.
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11-19-2018, 12:32 PM | #12 | |
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11-19-2018, 05:41 PM | #13 | ||
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--Dylan
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11-21-2018, 09:47 AM | #14 |
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I've looked at it witha 305/30/18, and it's very, very tight. You can't run any suspension that requires a spacer. It will require 3.5 degrees camber, etc...
There are a couple of people who say they have done it, but when I tried it with my 11" wheel I came to the conclusion it was a bridge too far. The other issue will be the tire will rub on the fender liners if it's a 35 profile as you turn it. No way around that. You can massage the liners a bit and that will most likely solve it. I did put a 305/30/19 on the front with a 19x10.5 et22 wheel. It fit, but would rub under turning until I massaged the liners a bit with a heat gun. The general issue on this car isn't getting the width as much as having a big enough opening to be able to turn it. There are coolers on the front of the wheel wells that you don't want to rub
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11-21-2018, 12:28 PM | #15 |
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It can certainly be done, but it is not a bolt-on fitment. It requires the right recipe of wheel specs, tire size, negative camber, spring configuration, etc.
For most enthusiasts, 18x10" ET25 front, 18x11" ET44 rear staggered fitment is most effective for both street and track duty. Pair these with 275/35-18 tires up front and 305-35-18 tires in the rear respectively (or a few other common tire configurations) and you have a great bolt-on fitment. With that said, many of our clients are serious track nuts, participate in time attack events, or compete W2W. Not only are they looking to maximize grip, but many desire a square fitment for a well balanced chassis with the ability to rotate wheels and tires on all four corners. In order rotate effectively, the wheel specifications needed to be cohesive from front to rear. This means that either the front or rear will need some level of "work" to properly fit an 11" square fitment. Option 1: Front & Rear: 18x11 ET44 Commonly paired with 295/30-18 or 305/645-18 tires The 18x11" ET44 was specifically designed for the rear of the F8X chassis, so naturally this is a direct fit out back. When we install these up front however, thick spacers are required for proper strut clearance. Breizh Motorsport's (more photos) chose to go this route, and installed 25mm spacers to clear their KW Competition suspension. Keep in mind, spacer thickness will depend on the front tire brand and suspension type, as not all are created equal. An 11" ET44 wheel paired with a 25mm spacer gives us an effective offset of ET19, so this ends up being quite an aggressive fitment on the outside/fender side and a healthy amount of negative camber will be required to bring the top of the tire in under the front fenders. Since you will (should) only find this type of fitment in the hands of racers, aggressive negative camber specs are par for the course and not a limiting factor. Option 2: Front & Rear: 18x11 ET25 Commonly paired with 295/30-18 or 305/645-18 tires The 18x11" ET25 was specifically designed for the rear of the E9X M3, and in this scenario it is better suited for front end as the lower offset lends itself to more inner strut clearance. Naturally, this transfers the focus to the rear of the car, where the 18x11" ET25 is very aggressive (28mm more aggressive then the factory 19x10" ET40 rear wheels). In effort for these to work when the car is put through its paces on the race track, rear fender modifications will likely need to be performed in the form of "pulling/re-shaping" in combination with additional negative camber. Brett Strom from Strom Motorsports (more photos) is well versed in this arena and no stranger to modifying factory fenders, therefore he chose to go this route. In some cases we have reports of customers using this square fitment with 305 tires without needing to modify the rear fenders, however adding -2 degrees or more of camber in the rear was still necessary. In conclusion, neither of these 11" square fitments are considered "bolt-on fitments" and should only be reserved for serious track/race cars. It is important to note that regardless of which offset you choose to use, compliant track oriented suspension equipped with linear springs and a spring perch location above the front tires will be required to maximize inner clearance to the strut. --Dylan
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11-21-2018, 04:18 PM | #16 |
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305/35 is 26.4" tall with a 25mm offset it will rub. I don't think this is going to work. Strom, and me for that matter, are running a 305/645/18 which is EQ to a 305/30/18 tire. The extra height of the 35 series is going to kill it.
I've tried the 305/30/19 which is 26.2" tall on an 10.5" rim with 22mm offset and it rubs the fender liners. It's workable with massaging, but it definitely rubs. Try it though and report back.
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11-23-2018, 06:19 PM | #17 |
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Also depends on tires. It's been mentioned that Pirelli DH slicks in 305/645-18 should clear fine, with some additional camber and spacing.
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12-10-2018, 02:22 PM | #18 | |
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Serious newb question :D
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If one weren't as interested in the traditional square setup, as simply being able to run 305 tyres all around... Would it be possible to run 18x11" ET44 on the rears and 18x11" ET25 on the fronts (i.e. combination of option 1 and 2), where reading the description for each option lends itself to believe that no spacers or negative camber will be required for either the rears or fronts? Thanks! |
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12-10-2018, 02:37 PM | #19 | |
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It can certainly be done, but there will likely still be some level of negative camber required up front to fit the 18x11" ET25, especially with a 305 tire. --Dylan
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12-10-2018, 02:44 PM | #20 | |
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Also, one further question, on performance, what effect on driveability will moving from the traditional square setup to this hybrid have? Thanks again! |
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12-10-2018, 03:21 PM | #21 |
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That's not going to happen unfortunately. There just isn't room between the strut and the outer fender lip for an 11" wheel with no camber. The camber has the effect of moving the strut inwards so it's directly adding room at the fender well. At less than 2 degrees camber an 11" wheel and 305 tire will stick out 1/2" or more past the fender even if you had zero space between the strut and the wheel.
I tried this with my rear street wheels (19x11 ET44-20mm spacer) and it was just a no go when using a 305/30/19. A 305/30/19 on a 10.5" rim will work if you have some camber and massage the fender liners as the diameter is too big to turn fully (tried that too). A 10.5" is about as wide as you can go up front and that will require camber if you are using a 305 or 295 tire. Everyone who is using the 11" front is doing so with Pirelli slicks. These are narrower than a lot of 295 tires, and are very short as well. That in combination with a lot of camber will allow it to work with that specific tire, or a lot of 295/30/18 tires. Unfortunately nobody makes a 305/30/18 tire. That would be perfect.
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12-10-2018, 03:55 PM | #22 |
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OK, so for a dual duty guy like me, an 18x11" ET44 wheel all around, with 25mm spacer up front, and 295/35 R18 tyres is probably the best solution. I couldn't find any 305 tyres to match an 18" wheel.
Thanks for all of the feedback! |
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