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Do 18s slow the car down at all,any difference to notice? Im looking at wheels and so far Ive narrowed my choices down to black bullits, anthracite fr500s or satin 03 cobras for my black 00 gt. I like the look of 18s but wouldnt they be bad for the track? my car is stock right now besides hpipe,exhaust and intake. My next mods will be 4.10s/sct tuner and some drag radials. Would I regret 17s? Tires for 18s look a lot more expensive :(
 

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I am in a similiar dispute. I want the look of the 18's but the grip and price of the 17's :p.

Sure the 18's are heavier but what really matters is its just that much more rim that your drivetrain and diff has to spin. That and your tire profile will be a lot shorter. Where as on 17's you can run 315's real nicely.

The way I kind of see it is, 18's are great for the street and 17's are great for street use and mild strip. If you were a track junky and wanted best of both worlds, you would use the 18's on the strip and some racestars or welds on the strip with some true drag radials.
 

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If 18's slow you down, I sure as hell haven't noticed.

Just recently I went up against an E36 BMW 3 series, running a single turbo at 16 PSI, tuned by Evolution Motorsports. From a slow roll (starting in 1st and 2nd), I got him a couple times, every time. No idea what sort of power it was making at 16 PSI. Seems like a big number to me since I'm used to hearing about the typical boosted GT making around 400 RWHP at 10 or so PSI with an exhaust and minor bolt ons.

However they're just a little 2.5 inline 6. I'd like to imagine around 300 crank HP, since they make a tad below 200 crank HP stock. Not sure of the drivetrain losses on bimmers, but it probably had a decent 240 or so RWHP. Took me a second to pull ahead of him.

Also went up against an L98 350 powered 1991 Firebird. Full bolt ons, tuned, headers. That also had to be a roll race. It was before I had my T56 swapped in, and I had no use of 2nd gear. He didn't have any use of 2nd gear either. 700R4 automatic car that wouldn't shift into 2nd at WOT for some reason. We ran at least 3 or 4 times, took him every time.

I have heavy 18x9 and 18x10 FR500s on 285 Sumitomos out back. Although I bet just running skinnies up front would make a big noticeable difference.
 

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Abyssinian of AX
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I am in a similiar dispute. I want the look of the 18's but the grip and price of the 17's :p.

Sure the 18's are heavier but what really matters is its just that much more rim that your drivetrain and diff has to spin. That and your tire profile will be a lot shorter. Where as on 17's you can run 315's real nicely.

The way I kind of see it is, 18's are great for the street and 17's are great for street use and mild strip. If you were a track junky and wanted best of both worlds, you would use the 18's on the strip and some racestars or welds on the strip with some true drag radials.
18"s are typically a heavier wheel, but I can just about guarantee you will never notice. Now, if looking to lighten up your ride for any particular reason, than every little bit helps and find a wheel that is of the style you like, yet lightest you can find.

As for diameter difference, the tires are gonna be exactly the same in most cases. Reguardless of wheel diameter, the tire diameter is best to be kept the same as OEM in most cases. This avoids some rubbing issues and retains speedometer accuracy, as well as the effective gearing of the final driveline ratio. Some will opt for larger or smaller diameter tires for a couple different reasons, but not going to get into that here. :

315/45/15" tire = 25.6" diameter (in theory, I don't see any made)
315/40/16" tire = 25.6" diameter (in theory, I don't see any made)
315/35/17" tire = 25.6" diameter
315/30/18" tire = 25.6" diameter

The advantage of going smaller wheel is the ability to run a higher profile tire for an improved launch and/or improved ride quality. There is MUCH more to the equasion than just this, but the jist to be sure :yes

Jazzer :)
 

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Just like Jazzer said there is much more to the equation, but ill through in my two cents.
At the track with lets say an average driver, your not going to notice a difference.
Im assuming you go to the track maybe 1 or 2 a year, ( just assuming ) so your probably not all about bracket racing and a die hard racer that needs to shave every tenth of your 1/4. So with that being said you will be happy with the 18s and will probably never notice at the track that you have 18s over 17s.

How ever if you went to the track with light weight 15s your probably going to notice a little difference over the 18s.

But i think the 18s and 17s are going to be close enough with an average driver that your never going to notice the difference.
 

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Abyssinian of AX
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^ :yes

The difference between the 15"s and 18"s is gonna be due to the "give" of sidewall WAY more than anything else. If one can have light-weight 15"s, will have the best of both worlds :D

Jazzer :)
 

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The total weight would be the biggest issue. In theory, a taller tire, or at least one with the mass located farther away from the axis of rotation has the greatest potential energy & inertia............Think of a 26" 10 speed bicycle vs. a 20" kids bike. The best would be a light, skinny but tall wheel with the majority of the mass located on the rim (i.e. Top Fuel dragsters). In the real world and on the street, if the weight is even close you'll never notice. This is in reference to the front wheels in the context of drag racing. Obviously, a taller rear tire changes effective gear ratio and can hurt acceleration unless accounted for.
 

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I have 1 set of each (17's & 18's). And I gotta admit I like the driving with the 18's more but when it comes to the strip 17's. :)
 

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Too Soon, Junior!
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Most likely you won't notice any difference in speed with 18s. They will actually allow you to push harder in the corners since there will be less area on the sidewall of the tire to flex. Tires are outrageously expensive though (especially good tires).
 

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If you are in to drag racing then the sidewall is your friend. A tall sidewall that flexes will grip a lot harder than the same compound on a short sidewall. If you are into curves then you really don't want that flex. Again, like suspension, it depends on what you want out of your car.

P.S. The assumption above is that you will reduce the sidewall of the tire to compensate for the extra diameter of the wheel. That is not true of newer cars. I have a friend that runs 245/45/19s. Same sidewall as our stock tire.

Edit: I would swear that my 8.75x14s that I ran on my 426 Dodge hook better that the wide tires of today. Of course the stock tire is about 9.8" wide and its suppose to last 50,000 miles. And the old tires would only last 20,000 mile. But its not just the difference of the compound of the tire, I really believe the sidewall makes a huge difference.
 
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