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Discussion Starter #1
I know they should fit the stock MS6 rims, but will I have rubbing issues? I need to go to at least an all season performance tire for winter here and there are better options for tires in the 225/45/18 size.
 

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I know they should fit the stock MS6 rims, but will I have rubbing issues? I need to go to at least an all season performance tire for winter here and there are better options for tires in the 225/45/18 size.
[/b]
you'll be fine.
 

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I am also considering 225/45/18s. They add about .2 inches to the radius. Please let us know if you follow through with the larger tires. Remember, larger tires are probably heavier which may be slower overall.

Keith_MS6
 

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I am also considering 225/45/18s. They add about .2 inches to the radius. Please let us know if you follow through with the larger tires. Remember, larger tires are probably heavier which may be slower overall.

Keith_MS6
[/b]

Is a 225/40 the same diameter as the stock 215s?

With all this talk about new tires already, maybe we should get a groupbuy together.
 

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Is a 225/40 the same diameter as the stock 215s?

With all this talk about new tires already, maybe we should get a groupbuy together.
[/b]
nope. 40mm is the sidewall height. stock is 45mm. so by going down to 225/40, u lose a total of 10mm in wheel diameter. this will throw off the speedometer also and you need to check the weight limit on the tires to make sure it can handle the 2 tons of the ms6 plus passengers and junk in the trunk.
 

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id be interested in a group buy on all season or snow tires.
 

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nope. 40mm is the sidewall height. stock is 45mm. so by going down to 225/40, u lose a total of 10mm in wheel diameter. this will throw off the speedometer also and you need to check the weight limit on the tires to make sure it can handle the 2 tons of the ms6 plus passengers and junk in the trunk.
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40 is not in mm, it's percent of the width (which is mm). So stock 215/45 would be 215mm wide and 96.75mm high and 225/40 is 225mm wide and 90mm high.
 

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Is the difference in tire diameter going from a 215/45 to a 225/45 going to be that big of a deal?

I see that the more common 225/40 is a bit smaller (diameter) than stock tires - is that going to affect anything? Will the speedo be accurate or will it have to be recalibrated?
 

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Discussion Starter #11
Is the difference in tire diameter going from a 215/45 to a 225/45 going to be that big of a deal?

I see that the more common 225/40 is a bit smaller (diameter) than stock tires - is that going to affect anything? Will the speedo be accurate or will it have to be recalibrated?
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The stock tires are 215/45/18 on a 18x7 wheel. The overall diameter is 25.7" A 225/45/18 tire on an an 18" wheel has an overall diameter of 25.9". A 225/40/18 tire on a 18" wheel has an overall diameter of 25.2" If you are going to a different tire size you want to try to keep the overall diameter within .3" of the stock diameter. The 225/40/18 is too much of difference and it will cause the speedo to be off. The 225/45/18 will not have any noticeable effect on the speedo.
 

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The 225/40/18 is too much of difference and it will cause the speedo to be off. The 225/45/18 will not have any noticeable effect on the speedo.
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That's too bad since there are a lot more tire options in the 225/40/18 size - oh well...
 

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That's too bad since there are a lot more tire options in the 225/40/18 size - oh well...
[/b]
Since this was brought up, has anyone checked their stock (215/45x18) tire set up with speedometer readings? I drive by one of those neighborhood radar signs near a school everyday that gives you your speed readings when driving down the block. It will state I am driving 26 mph when my speedo states 29 mph. Which is correct? If my speedo is optimistic, the error at highway speeds is much higher than at 26 mph. :goon:

If this is true, then the stock tire set up would be too small in overall diameter, thus spinning more than actual speed. A slightly larger tire diameter would correct this. Or is there a calibration the dealer can perform? Reason? Who wants more mileage on their vehicles than they are actually driving.

Think about it, for even a 3% deviation, at 10,000 miles this works out to 300 miles, 50,000 miles / 1,500 miles. You will get less use from the car when it comes time to sell it. (but who is really going to let their MPS ever go any ways?)

Who else has comfirmation with another radar source? :)

Adam
06 Mazdaspeed6 GT
Blk/Blk
 

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Since this was brought up, has anyone checked their stock (215/45x18) tire set up with speedometer readings? I drive by one of those neighborhood radar signs near a school everyday that gives you your speed readings when driving down the block. It will state I am driving 26 mph when my speedo states 29 mph. Which is correct? If my speedo is optimistic, the error at highway speeds is much higher than at 26 mph. :goon:

If this is true, then the stock tire set up would be too small in overall diameter, thus spinning more than actual speed. A slightly larger tire diameter would correct this. Or is there a calibration the dealer can perform? Reason? Who wants more mileage on their vehicles than they are actually driving.

Think about it, for even a 3% deviation, at 10,000 miles this works out to 300 miles, 50,000 miles / 1,500 miles. You will get less use from the car when it comes time to sell it. (but who is really going to let their MPS ever go any ways?)

Who else has comfirmation with another radar source? :)

Adam
06 Mazdaspeed6 GT
Blk/Blk
[/b]
mine was right on. clocked at 35 while going 35.
 

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Who else has comfirmation with another radar source? :) [/b]
One of the best calibration tests is by using a handheld GPS, such as a Garmin model typically used for hiking. They're accurate to about 0.1 mph. They do show your speed averaged over the past few seconds, however, so test it against some constant highway cruising.

My car reads high by only 1.3 mph at 70 mph (I'm really going 68.7 when my speedo is pegged at exatly 70).

My old car was about 10% high. I'm so used to seeing 80 mph on my speedo and thinking I'm only doing 72, that I'm having a tough time reprogramming myself.

By the way, almost all cars will read high by some amount as set from the factory. How much will vary.
 

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whenever I pass one of those radar signs it just flashes 00

:)
[/b]

Cheater! :)
 
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