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Discussion Starter · #1 ·
I'd like to hear the pro's and con's from those MS6 owners that switched to 225/40/18.

1) I know that the speedo (and odometer) will read a bit higher ... is that a big deal?
2) Is the ride too harsh, due to the smaller sidewall?
3) Is there a big improvement in grip, due to the larger width?
4) Is acceleration compromised, due to having to shift sooner?
5) Any impact on fuel economy?
6) Any other pro's or con's?

Thanks!
 

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+1 would love to hear any/all of these questions answered
 

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I don't think that fuel economy me would be effected, at least I can't see why. For the harsher ride I also doubt that it would be much different than it already is. I'm not sure about the others though.
 

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I'd like to hear the pro's and con's from those MS6 owners that switched to 225/40/18.

1) I know that the speedo (and odometer) will read a bit higher ... is that a big deal?
2) Is the ride too harsh, due to the smaller sidewall?
3) Is there a big improvement in grip, due to the larger width?
4) Is acceleration compromised, due to having to shift sooner?
5) Any impact on fuel economy?
6) Any other pro's or con's?

Thanks!
[/b]
1) Not really, slight difference but speedo calibration can correct it.
2) It's more harsh, yes, depends on your comfort/performance trade-off expectations
3) Definitely
4) Haven't noticed.
5) Haven't tested. Don't care.

Hope that helps.
 

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wont the 225's be heavier? more rotating mass is bad for acceleration....not sure and I know certain tires weigh alot more than others also.

wont the 225's be heavier? more rotating mass is bad for acceleration and fuel economy....not sure about the weights exactly - tirerack lists it I believe. And I know certain tires weigh alot more than others also.


with that said - my next set will probably be GS-D3's in 225 size
 

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I haven't switched to 225/40-18. I'm running 235/40-18 which is already slightly smaller than stock. According to my calculations, a 225/40 is more than 3% different from stock, which is normally the maximum recommended deviation.

A 225/40-18 has the following nominal values (ie. based on the numerical values, real tires can vary from these):
Overall diameter of 25.09 inches, circumference of 78.8 inches.
A 215/45-18 tire has the following nominal values:
Overall diameter of 25.62 inches, circumference of 80.47 inches.

The difference is 3.46%, and the 225/40-18 tire will show 60mph on the speedometer while actually going only 58mph.

The ride will depend a lot on the tire you choose, but the smaller sidewall definitely won't help it any. There are some ultra low profile tires that have been designed to give a decent ride even with little sidewall. On the other hand, there are all out performance tires that will make you feel that you're rolling on a solid strip of rubber. On the other hand, turn-in will probably be crisper, due to less sidewall to flex.
 

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I'd like to hear the pro's and con's from those MS6 owners that switched to 225/40/18.

1) I know that the speedo (and odometer) will read a bit higher ... is that a big deal?
2) Is the ride too harsh, due to the smaller sidewall?
3) Is there a big improvement in grip, due to the larger width?
4) Is acceleration compromised, due to having to shift sooner?
5) Any impact on fuel economy?
6) Any other pro's or con's?

Thanks!
[/b]
1) The speedometer and odometer will show approximately 2.2% more than what you would with stock. The prefered difference is <2% but you will be close enough.
2) The smaller sidewall could make a difference but it is almost entirely dependent on the type of tire you use.
3) 10mm of width will only make a huge difference if you are already running 8/10 or more. Hopefully that will not be the case on the street :p
4) At 60mph in the 215/45 you will be going about 58.7 with the 225/40. Almost negligable unless you are really riding out a gear on the dragstrip.
5) It's doubtfull that it will make difference that you will be able to see. The compound and tread of the tire will make more of a difference.
6) Lighter is better! Not to mention 17" tires are a lot cheaper in most cases than 18". If you have the means a nice light set of 17" wheels and tires will solve all your problems.

Quick edit: I got my information from http://www.wheelsmaster.com/rt_specs.jsp. Its the place I used to pick out my wheel/tire set to get it as close as possible.
 

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what are the pros/cons of 225/40/18 to 225/45/18 on 8" rims? for the time being at least i'll keep the stock springs. i've never been one to change up stock size tires, but the car despritely needs to upsize from 215s.
 

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1) The speedometer and odometer will show approximately 2.2% more than what you would with stock. The prefered difference is <2% but you will be close enough.
2) The smaller sidewall could make a difference but it is almost entirely dependent on the type of tire you use.
3) 10mm of width will only make a huge difference if you are already running 8/10 or more. Hopefully that will not be the case on the street :p
4) At 60mph in the 215/45 you will be going about 58.7 with the 225/40. Almost negligable unless you are really riding out a gear on the dragstrip.
5) It's doubtfull that it will make difference that you will be able to see. The compound and tread of the tire will make more of a difference.
6) Lighter is better! Not to mention 17" tires are a lot cheaper in most cases than 18". If you have the means a nice light set of 17" wheels and tires will solve all your problems.

Quick edit: I got my information from http://www.wheelsmaster.com/rt_specs.jsp. Its the place I used to pick out my wheel/tire set to get it as close as possible.
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Thanks for the link, using that I see that my new tires/wheels (225/45/18s) are 25.9" tall vs. 25.6" stock, so they are actually .3" taller. This should make the speedo SLOWER by some %, correct? Larger tire=larger cirmcumfrence=less rotations per mile. Anyone have numbers on what that difference would be?

Also, for Nav owners, how do I calibrate the Nav (and the speedo for that matter) to the new tires sizes?

As to weight issues, I know my tires are a little heavier, but the new rims I bought are 5lb lighter per corner, so I *hope* I still came out lighter in rotational inertia, though I should have weighed them before mounting to be sure. Car feels lighter anyway :)

Thanks
 

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Discussion Starter · #10 ·
I haven't switched to 225/40-18. I'm running 235/40-18 which is already slightly smaller than stock. According to my calculations, a 225/40 is more than 3% different from stock, which is normally the maximum recommended deviation.

A 225/40-18 has the following nominal values (ie. based on the numerical values, real tires can vary from these):
Overall diameter of 25.09 inches, circumference of 78.8 inches.
A 215/45-18 tire has the following nominal values:
Overall diameter of 25.62 inches, circumference of 80.47 inches.

The difference is 3.46%, and the 225/40-18 tire will show 60mph on the speedometer while actually going only 58mph.

The ride will depend a lot on the tire you choose, but the smaller sidewall definitely won't help it any. There are some ultra low profile tires that have been designed to give a decent ride even with little sidewall. On the other hand, there are all out performance tires that will make you feel that you're rolling on a solid strip of rubber. On the other hand, turn-in will probably be crisper, due to less sidewall to flex.
[/b]
Will the 235/40/18 fit on 18x7.5" Rims? Discount Tire Direct says yes, but, Tire Rack and the manufacturers websites say no.

Any rubbing with 235/40/18's?
 

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Will the 235/40/18 fit on 18x7.5" Rims? Discount Tire Direct says yes, but, Tire Rack and the manufacturers websites say no.

Any rubbing with 235/40/18's?
[/b]
I put 235/40/18 goodyear eagle f1 gs-d3's on 18x7.5 wheels. Some tire companies will say not to but any tire place I asked said it would be fine. May depend on what tire your using since some are wider than others for a given width (225 is not the sam width on all tires) but they should fit fine. Sidewalls wont be as effective on a 7.5" rim as it would on an 8' rim, but should still be fine.
 

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Thanks for the link, using that I see that my new tires/wheels (225/45/18s) are 25.9" tall vs. 25.6" stock, so they are actually .3" taller. This should make the speedo SLOWER by some %, correct? Larger tire=larger cirmcumfrence=less rotations per mile. Anyone have numbers on what that difference would be?

Also, for Nav owners, how do I calibrate the Nav (and the speedo for that matter) to the new tires sizes?

As to weight issues, I know my tires are a little heavier, but the new rims I bought are 5lb lighter per corner, so I *hope* I still came out lighter in rotational inertia, though I should have weighed them before mounting to be sure. Car feels lighter anyway :)

Thanks
[/b]
Yes your car will be going slightly faster than that the speedometer is showing and you will rack up less miles on the odometer than you would going over the same road with the stockers. According to that site that I posted it shows approximately .7mph difference at 60mph. Well within acceptable range.

Don't forget, while overall weight might have gone down you still have more weight at the outside edge of the wheel which will be more pronounced than weight towards the hub of the wheel. Honestly though unless you are trying to shave .01 seconds off your 1/4 mile time you will probably not notice a big difference on the street.

There is a lot more info in the Tire/Wheel section of this board too. I got that link from the sticky there. While the 16" won't fit the speeds most of the 17"+ wheel/tire combos that people are running on the regular 6 will work for us too. Plus Toyoguy posts there a lot and he is a wealth of information in himself :yesnod:
 

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Excuse me for being a little off topic, but I would definitley like to know how to "calibrate" the speedo. Seems mine needs it, and I haven't changed anything.

Did anyone else see a stock speedo error. In my car with the stock 215/45-18's I am at 50 indicated going barely 49, and 80 indicated going only 78 (on my handheld gps).

I'd actually like to go up to 225/45-18's to combat this. I plan on buying the car at lease end if it holds together well, but if I end p tading it in I don't want the speedo to show 500 extra miles on every 20k....
 

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I'd like to go to a 225/45/18 as well. The rims I have are 18x7.5 and offset is 42+. will that rub w/o rolling the fenders?
 

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Yes your car will be going slightly faster than that the speedometer is showing and you will rack up less miles on the odometer than you would going over the same road with the stockers. According to that site that I posted it shows approximately .7mph difference at 60mph. Well within acceptable range.

Don't forget, while overall weight might have gone down you still have more weight at the outside edge of the wheel which will be more pronounced than weight towards the hub of the wheel. Honestly though unless you are trying to shave .01 seconds off your 1/4 mile time you will probably not notice a big difference on the street.

There is a lot more info in the Tire/Wheel section of this board too. I got that link from the sticky there. While the 16" won't fit the speeds most of the 17"+ wheel/tire combos that people are running on the regular 6 will work for us too. Plus Toyoguy posts there a lot and he is a wealth of information in himself :yesnod:
[/b]
Great, thanks for the input!
 
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