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Discussion Starter #1
Will this size fit? Tirerack's got the Kumho MX at this size for $120. Will be a great fit for STS. :D or will it be too heavy?
 

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I would go 215/50/17, but not 225/45. For one, I don't think this car needs wider tires. And I don't think it's a good idea to mess drastically with something as critical as the tire width on a car that handles this good stock.

Weight is definitely a factor. Others are rim width, fender clearance, turn clearance, steering system stress, and stability on imperfect roads.

Edit: I'd also add hydroplaning and snow traction.
 

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How wide are the stock wheels? If they're 7", you should be good.

FYI, stock tire size is 205/50/17... going to 215/50/15 would result in your speedo reading 1.6% too slow. Going to 225/45/17 would result in a speedo reading of 0.4% too fast, meaning it's a better match size-wise... as long as it fits.

If you're looking specifically for autocross, Falken makes Azenis in that size... not sure how much they cost, though.
 

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225 seems excessive - 205 is thre best for the 3, although you can make a case for the 215 too - but 225? As Lee said, way too wide for any type of wet driving
 

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dinu01 said:
225 seems excessive - 205 is thre best for the 3, although you can make a case for the 215 too - but 225? As Lee said, way too wide for any type of wet driving
STS=autocross. Autocross=not caring about wet driving.
;)

From a bit of personal experience, I've had Pirelli P7000 SS tires on my 94 Probe GT in 225/45/17 (stock was 225/50/16); they were just fine in the wet. I'd imagine that, given the poster is in Hawaii, snow driving is not a concern.
 

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Oops! :)

But wouldn't a tire that's too wide create too much friction (with the thread in a straight line and with the sidewall in turns) and wind resistance?

Just some thoughts...
 

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Not really. More than anything, the biggest difference will be weight. Heavier tires take more power to turn, and thus can reduce acceleration times slightly. They will, however, provide more cornering grip due to the changed contact patch and stiffer sidewalls. Hydroplaning resistance will depend largely on rubber ccmposition and tread design. I'd wager that S03s in 225/45/17 (hypothetically) would have better wet traction than the stock tires. It all depends on what the tire is designed to do.

Keep in mind that 225 is not a large tire width; in fact it's quite common on many touring sedans, and on the small side for performance tires.

To read up on lots of tire stuff, I'd suggest the Tire Rack's site... go to the tech center.
 

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Discussion Starter #8
Wow, great response guys. Keep it coming. If I do get the Mz3, then perhaps I will get some lightweight 17x7 for the front and wrap some kumho MXs in 225/45/17. Too bad STS doesn't allow rim widths more than 7.5, or else the SSR comps in 17x8 would be great! :D
With the rear tires stock, perhaps it will be able to rotate pretty well and turn in good times?
Tirerack doesn't sell Azenis. :cry: Other tire dealers charge an arm and a leg for shipping, so I'm stuck with only Kumho as an affordable performance tire choice.
 

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The stock wheel is 17x6.5. So going to an 18x7.5 is going to a rim that is a full inch wider. Finding another inch of clearance in there is going to be an iffy proposition. You'll need to be very careful with the offset.

Hydroplaning happens when the tire momentarily leaves the road surface because water cannot be displaced fast enough. In otherwords, the tires become water skis. Effective tread design that channels water away quickly is the best way to fight hydroplaning. However, wider tires necessarily displace more water and have a harder time doing it because the resistance encountered by an object moving through water goes up by square of the increase in surface area of the object. Given two tires of the same tread design and depth, the wider tire will absolutely be more prone to hydroplaning. Going from 205 to 225 is an increase of 10%, meaning the hydroplaning force will increase by about 21%.

Granted, many cars come with 225mm wide tires stock, but these cars are designed for tires of such width, whereas the Mazda3 is not. Heavier cars can safely run a wider tire because their weight counters the additional lift from the wider tires.

In terms of speedometer error, I did some research and found that many 215/50/17 tires offer the similar actual diameter and roll out as the stock 205/50/17 tires, which would result in minimal speedometer error. Manufacturers do not adhere to the ratios perfectly, and consequently not all 215/50/17 tires have a 107.5mm high side wall.
 

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slipangle said:
Tirerack doesn't sell Azenis. :cry: Other tire dealers charge an arm and a leg for shipping, so I'm stuck with only Kumho as an affordable performance tire choice.
You should do more research. There are plenty of alternatives to the Tire Rack, including Discount Tire Direct and Vulcan Tires, both of which carry Azenis, and both of which ship via UPS, just like Tire Rack. DTD has them for $117ea in 225/45/17... cheaper than the Khumos from Tire Rack. I cannot vouch for their fit on the stock 17" 3 wheels, though.

LeeLee said:
The stock wheel is 17x6.5. So going to an 18x7.5 is going to a rim that is a full inch wider.
While that's true, nowhere in this thread is there any mention of changing wheel size. This is about what will fit on the stock rims ;)


Kirk said:
FYI, stock tire size is 205/50/17... going to 215/50/15 would result in your speedo reading 1.6% too slow. Going to 225/45/17 would result in a speedo reading of 0.4% too fast, meaning it's a better match size-wise... as long as it fits.
Error on my part: I mean 215/50/17, not 215/50/15.
 

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Kirk said:
LeeLee said:
The stock wheel is 17x6.5. So going to an 18x7.5 is going to a rim that is a full inch wider.
While that's true, nowhere in this thread is there any mention of changing wheel size. This is about what will fit on the stock rims ;)
No more morning beer for me.
 

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slipangle said:
KIRK...UPS shipping to Hawaii is horrendous.
Didn't know that. Isn't there a local tire store that carries Falkens? Maybe they'll price match. I believe Sears can get them, and I see there are some in Honolulu... Just offering ideas.
 

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Discussion Starter #14
LEELEE...think Kirk is right about hydroplanning. I upgraded from 185/70/14 stock tire size (yeah, real old car that I'm attempting to autocross) to 205/60/14. With the ES100s in the fronts, my wet traction is actually better than whatever crappy tire I bought this car with. I even have bald 205/60/14 sumitomo HTR200s in the rears with no traction issues. Guess the ES100s in the front clear the contact patch for the rears to follow. This setup gives me good rotation for autocross style driving. Probably wouldn't recommend it for 'normal' drivers though.

KIRK...yeah, SEARS has Falkens, but not azenis, and as far as I know, no one is using Azenis here in Hawaii, cept one guy who DID pay for the shipping from the mainland. TIrerack charges me about 15 bucks a tire for shipping, UPS charges like a freaking $50 or something like that. :x
 

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slipangle said:
LEELEE...think Kirk is right about hydroplanning. I upgraded from 185/70/14 stock tire size (yeah, real old car that I'm attempting to autocross) to 205/60/14. With the ES100s in the fronts, my wet traction is actually better than whatever crappy tire I bought this car with. I even have bald 205/60/14 sumitomo HTR200s in the rears with no traction issues. Guess the ES100s in the front clear the contact patch for the rears to follow. This setup gives me good rotation for autocross style driving. Probably wouldn't recommend it for 'normal' drivers though.
Wet traction and hydroplaning are different. Wet traction is just how well the tire holds onto the road despite it being wet. Hydroplaning is the propensity for a tire to lose contact with the road at speed. When hydroplaning, the wet traction of the tire is zero. Just because a tire has good wet traction doesn't mean it is well desgined against hydroplaning.

Wet traction may go up with a wider tire because the contact patch has changed. Also, you have gone with a different tire with a different compound and different tread design. It is only natural that a better designed tire would provide better wet traction. But if you take two tires of the exact same design, one 185mm wide and one 205mm wide, the 185mm wide tire will be less prone to hydroplane.
 

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Discussion Starter #19
Well, tirerack fits the 215/45/18 to the Mz3. My guess is 225 will fit in the fronts, but not so sure in the rear. Front wheelwells are usually larger for FWD cars. Who wants to be a guinea pig for us eh?
 

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I don't think 225/xx/17 is a good idea on the stock wheels. They are designed for 7.5in. wheels (rim range 7.0-8.5in.) as shown on the Sumitomo website for its 225/45/17 tire. But I don't think they would rub anything if you do decide to go with 225. I'm thinking about getting some 17x7.5 rims with 225/45/17 tires myself.
 
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