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Old 05-23-2012, 06:37 PM   #1
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Default Are 0 offset wheels slow?

Hi guys,

I currently run a set of 15x7 OZ Superleggera wheels which are lightweight, and allow me to run cheap rubber in 195 width. I'm nearing completion of my engine build, and with more power I'm going to have to move to a wider tyre to put the power down properly.

6UL are nearly impossible to find in the UK, and the only company I've found who import them have sold their entire stock and don't have an ETA for any more deliveries. I've also considered the Rota K7.

Here's the tricky part - 225/45/15 tyres are rare as rocking horse ---- in the UK. Nobody sells them. So much so that there are almost no options for street tyres available. I've found ONE place who sells them and they're R888 and consequently they're expensive.

Which brings me onto an 8 inch rim and a 205 section tyre. This size tyre is commonly available and a lot cheaper. I'm looking at Rota Grid V and running a 205/50/15 tyre under some flares.

I've heard people say 0 offset wheels aren't fast. Does anyone have any solid experience to back this up? I don't understand why? You'd think the wider footprint would be more stable, but I'm not an expert and that's why I'm asking. I won't be slammed and I'll have flares, so rubbing in the arch won't be an issue.

The other option with flares is running a 16 inch wheel, which opens up a lot more options for running wide tyres but I'm not convinced with a 16 inch rim on an NA.

To cut a long story short: If you couldn't run 225/45/15 tyres, what would be the next fastest set up? Thanks.
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Old 05-23-2012, 06:47 PM   #2
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275/35/15
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Old 05-23-2012, 06:53 PM   #3
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I should make this multiple choice:

1. Keep the 15x7 ET36 and run 205/50/15 under stock arches
2. 15x9 Rota K7 (ET36?) and 225/45/15 under stock arches
3. 15x8 Rota Grid V ET0 with 205/50/15 with flares
4. 15x8 Rota Grid V ET0 with 225/50/15 with flares
5. None of the above - suggest an alternative.
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Old 05-23-2012, 06:55 PM   #4
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I hate going to that site...but as far as your title about a wheel being slower:

http://www.miata.net/garage/offset.htm
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Old 05-23-2012, 07:01 PM   #5
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Tried motmotorsport.co.uk? (Mazda On Track) Ask for Nick, he should be able to help you out.
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Old 05-23-2012, 07:04 PM   #6
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Yup I spoke to MOTmotorsport and the delivery he's getting very shortly are all spoken for. The whole reason the 6UL is nice is because you can fit the 225/45 tyre under the stock arch. When it's not easy to find those tyres it takes away the appeal.

225/50/15 is an easy tyre to source but I'd think it'd be too tall to fit under stock body work.

Edit - thanks for the link but it's not really proof that a 0 offset will perform worse. I understand what it says about reducing the scrub radius, but it also says it can add stability. I'd like to hear from people who have run a 0 offset wheel and can explain why it was good or bad.
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Old 05-23-2012, 07:18 PM   #7
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That's like asking heroin addicts to discuss the pros and cons of addiction - you're not really going to get an informed opinion.

You are turning two tires the same amount, and they want to travel the same radius as a result. Because one tire is further in than the other, it wants to travel a shorter radius, and it therefore scrubs. When you increase the track width of the car with +0 offset wheels, you make this scrubbing worse, and that slows the car down mid-corner, which harms corner exit.

Then there's the aero aspect - you're exposing a ton of tire, and even if you flare the car and shroud the tire in fully, you've increased the frontal area and therefore increased the drag.

+0 is slower - it's not a subjective thing. It's a math and physics thing.
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Old 05-23-2012, 07:22 PM   #8
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I have zero offset wheels because they came on my car. I'm still in the process of getting my car set up to run well at the track so for now they seem fine. the previous owner hacked up the front fenders so these wheels would fit. I would not buy zero offset for track but if you have them run them. some say they are harder on the wheel bearing but I dont know how true it really it but I guess it makes sense.

once I get everything set I hope to buy new wheels and suspension next year
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Old 05-24-2012, 02:35 AM   #9
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Quote:
Originally Posted by Savington View Post
You are turning two tires the same amount, and they want to travel the same radius as a result. Because one tire is further in than the other, it wants to travel a shorter radius, and it therefore scrubs. When you increase the track width of the car with +0 offset wheels, you make this scrubbing worse, and that slows the car down mid-corner, which harms corner exit.

+0 is slower - it's not a subjective thing. It's a math and physics thing.
Any thoughts on how the above will affect the new 10's? The 25 offset of the 10's vs the 36 offset of the 9's means the rims stick out 24mm more. Because the difference is split with the wider rim the tire only sticks out 13mm more than with the 9's. As previously discussed the wider 10's should be faster. I wonder how much the additional scrub will negate those gains.

Getting tired of all this key board racer ----. I need to get my act together and start logging in track days.
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Old 05-24-2012, 03:04 AM   #10
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Quote:
Originally Posted by k24madness View Post
Any thoughts on how the above will affect the new 10's? The 25 offset of the 10's vs the 36 offset of the 9's means the rims stick out 24mm more. Because the difference is split with the wider rim the tire only sticks out 13mm more than with the 9's. As previously discussed the wider 10's should be faster. I wonder how much the additional scrub will negate those gains.
Scrub radius is one of the reasons why wide tires are slower on low-power cars. If you have the power to be thinking about 245s, you probably don't need to be concerned with scrub radius.

The 10s would be faster with a higher offset, but pesky things like the shock towers prevent it.
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Old 05-24-2012, 03:22 AM   #11
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If you're willing to pay for the shipping my folk live in N. England. IE: If you ship them to me I can ship to their APO in Harrogate and you can go pic them up. My dad has nothing that fits 4x100 so he won't steal them. Maybe I can convince him to get me a set for B-day hehe. I know it's not cheap but it's an option for you to get 6ul's. Maybe you can save a few bucks on the exchange rate buying them in 'Merican monies and put it toward shipping.
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