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Discussion Starter · #1 · (Edited)
Since this seems to coming up once per week, I thought I'd make a quick post about tire sizes.

Note: Some of these sizes won't actually exist while others will only exist for "truck" tires (which is fine).

This post assumes that your wheels are fairly close in dimensions (width, offset, backspacing, etc) to the OE wheels.

Ideally, you want to keep the new size within 3% of the original size. If you have AWD, you want all four tires to be the same size, make, and model (because tires of different make/model with identical "sizes" can actually be noticeably larger or smaller than each other).

This list is by no means comprehensive. With correct attention to detail and fine tuning, you can probably go wider than 245. However, as you go with wider tires, you'll need wider wheels. If you go with wider wheels, you'll need to start paying attention to wheel offset otherwise you may find that the wheel or tire interferes with suspension components (i.e. you'll need go with a lower offset to push the wheel out a bit). But, if you push the wheel out too far, the tires may rub on the fenders.

Tire sizes that should fit OEM wheels
16"
Code:
Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
215/50-18         4.2in  13.2in    26.5in         83.1in        762        0.0% (Factory Touring and Grand Touring tire size)

205/60-16         4.8in  12.8in    25.7in         80.7in        785       -2.9%
205/65-16         5.2in  13.2in    26.5in         83.2in        761        0.1%
215/60-16         5.1in  13.1in    26.2in         82.2in        771       -1.2% (Factory Sport tire size)
215/65-16         5.5in  13.5in    27.0in         84.8in        747        2.0%
225/55-16         4.9in  12.9in    25.7in         80.9in        783       -2.7%
225/60-16         5.3in  13.3in    26.6in         83.7in        757        0.6%
235/55-16         5.1in  13.1in    26.2in         82.2in        770       -1.1%
235/60-16         5.6in  13.6in    27.1in         85.1in        744        2.4%
17"
Code:
Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
215/50-18         4.2in  13.2in    26.5in         83.1in        762        0.0% (Factory Touring and Grand Touring tire size)

205/60-17         4.8in  13.3in    26.7in         83.8in        756        0.8%
215/55-17         4.7in  13.2in    26.3in         82.7in        767       -0.6% (Closest matching 17" tire size)
215/60-17         5.1in  13.6in    27.2in         85.3in        743        2.6%
225/50-17         4.4in  12.9in    25.9in         81.2in        780       -2.3%
225/55-17         4.9in  13.4in    26.7in         84.0in        754        1.1%
235/50-17         4.6in  13.1in    26.3in         82.5in        768       -0.8%
235/55-17         5.1in  13.6in    27.2in         85.4in        742        2.7%
18"
Code:
Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
215/50-18         4.2in  13.2in    26.5in         83.1in        762        0.0% (Factory Touring and Grand Touring tire size)

205/55-18         4.4in  13.4in    26.9in         84.4in        750        1.6%
215/50-18         4.2in  13.2in    26.5in         83.1in        762        0.0%
225/45-18         4.0in  13.0in    26.0in         81.6in        777       -1.9%
225/50-18         4.4in  13.4in    26.9in         84.4in        751        1.5%
235/45-18         4.2in  13.2in    26.3in         82.7in        766       -0.5%
235/50-18         4.6in  13.6in    27.3in         85.6in        740        3.0%
Tire sizes for non-OEM wheels.
17", wider wheel recommended
Code:
Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
215/50-18         4.2in  13.2in    26.5in         83.1in        762        0.0% (Factory Touring and Grand Touring tire size)

245/50-17         4.8in  13.3in    26.6in         83.7in        757        0.7% *
245/45-17         4.3in  12.8in    25.7in         80.7in        785       -3.0% *
* You can probably get these to fit on the OEM-like 17x7 wheels but I don't recommend it. You'll want at least 17x7.5, preferrably 17x8.


18", wider wheel recommended
Code:
Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
215/50-18         4.2in  13.2in    26.5in         83.1in        762        0.0% (Factory Touring and Grand Touring tire size)

245/40-18         3.9in  12.9in    25.7in         80.8in        784       -2.8% **
245/45-18         4.3in  13.3in    26.7in         83.8in        756        0.8% **
*** You can probably get these to fit on the OEM 18x7 wheels but I don't recommend it. You'll want at least 18x7.5, preferrably 18x8.

19"
Code:
Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
215/50-18         4.2in  13.2in    26.5in         83.1in        762        0.0% (Factory Touring and Grand Touring tire size)

205/45-19         3.6in  13.1in    26.3in         82.5in        768       -0.8%
205/50-19         4.0in  13.5in    27.1in         85.0in        745        2.3%
215/40-19         3.4in  12.9in    25.8in         81.0in        783       -2.6%
215/45-19         3.8in  13.3in    26.6in         83.6in        758        0.6%
225/40-19         3.5in  13.0in    26.1in         82.0in        773       -1.4%
225/45-19         4.0in  13.5in    27.0in         84.7in        748        1.9%
235/35-19         3.2in  12.7in    25.5in         80.0in        792       -3.7%
235/40-19         3.7in  13.2in    26.4in         82.9in        764       -0.2%
245/35-19         3.4in  12.9in    25.8in         80.9in        783       -2.7%
245/40-19         3.9in  13.4in    26.7in         83.9in        755        1.0%
20"
Code:
Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
215/50-18         4.2in  13.2in    26.5in         83.1in        762        0.0% (Factory Touring and Grand Touring tire size)

205/40-20         3.2in  13.2in    26.5in         83.1in        762       -0.0%
205/35-20         2.8in  12.8in    25.6in         80.6in        786       -3.1%
205/40-20         3.2in  13.2in    26.5in         83.1in        762       -0.0%
205/45-20         3.6in  13.6in    27.3in         85.7in        740        3.0%
215/35-20         3.0in  13.0in    25.9in         81.4in        778       -2.0%
215/40-20         3.4in  13.4in    26.8in         84.1in        753        1.2%
225/35-20         3.1in  13.1in    26.2in         82.3in        770       -1.0%
225/40-20         3.5in  13.5in    27.1in         85.1in        745        2.4%
235/35-20         3.2in  13.2in    26.5in         83.2in        762        0.0%
245/30-20         2.9in  12.9in    25.8in         81.0in        782       -2.6%
245/35-20         3.4in  13.4in    26.8in         84.0in        754        1.1%
These data were produced using the Miata.net tire size calculator.
 

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Discussion Starter · #2 · (Edited)
Personal anecdote time:
I have personally fit 225/45-18 Kumho Ecsta TA71 tires on 18x8 ET50 rims (OE RX-8 wheels) on my car and they are fine. Also, 245/40-18 Hankook Ventus R-S3 (version 2) on 18x8 ET38 wheels (Sport Edition A7 a.k.a. ASA JH3) fit with just a hint of rubbing on the plastic fender liner at full steering lock.
 

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Thank you for these alternative tire sizes. I'm going to install the highly rated Michelin Pilot Sport A/S +3 (235/45-18) replacing the poorly rated OEM Yokohama Avids (215/50/18) (according to Consumer Reports). The only other all season tire available in the original size is the Pirelli P7 and that's considered just an "average" tire.
 

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Thank you for these alternative tire sizes. I'm going to install the highly rated Michelin Pilot Sport A/S +3 (235/45-18) replacing the poorly rated OEM Yokohama Avids (215/50/18) (according to Consumer Reports). The only other all season tire available in the original size is the Pirelli P7 and that's considered just an "average" tire.
How did this turn out for you?

I am very tempted to do the same. Spent all day looking for all-season tires that would fit my car and there aren't ANY!!! Might go for the Bridgestone Turanza T001 (215/50-18) due to lack of choice.
 

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I probably won't buy new tires until the spring and they're likely to be Michelins 235/45-18s.
 

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Discussion Starter · #6 ·
Ever since road debris took out the OEM front left tire on my CX-3, I've been running my old semi-race tires (Hankook Ventus R-S3) on the car.
I found a freaking steal of a deal on a set of new Michelin Pilot Super Sport tires in 235/50-18 ($500 shipped for the set, not counting the $100+ in MIR) so I jumped on them.

I just mounted them up yesterday.
First off, these suckers mounted really easily (buddy showed me how to use his tire mount/balance machines). They balanced even easier. Two wheels needed 1oz, another 0.75oz, and the third 0.50oz.
Second, holy crap are they an improvement over the 'Kooks. I understand the crazy love people have for these tires now. I have no doubt that the 'Kooks have much more grip for track/autocross. But the MPSS is just so quiet, soft, and comfortable comparatively that I don't even care for a street-driven car.

If you're looking for a good deal on very good summer tires to fit the OEM wheels...
https://www.discounttiredirect.com/buy-tires/michelin-pilot-super-sport/p/34216
 

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I bought a set of Yokohama Advan Sport A/S in size 225/50/18 a few months ago. I paid less than I would have for the OEM tires. The tire salesman said that the factory rims could easily go with 235/50/18, but I think that the 235s would do better on a wider rim. The 235s were more expensive than the 225s, and I did not see where it was worth it for the extra 10 mm.
 

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I recently replaced the OEM Yokohama Avids 215/50/r18s with the highly rated Michelin Cross Climate+ 235/45/r18s. They are so far fantastic. When not looking at the speedometer, I have found myself making turns 15 mph faster than before, they really grip the road.
 

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Ever since road debris took out the OEM front left tire on my CX-3, I've been running my old semi-race tires (Hankook Ventus R-S3) on the car.
I found a freaking steal of a deal on a set of new Michelin Pilot Super Sport tires in 235/50-18 ($500 shipped for the set, not counting the $100+ in MIR) so I jumped on them.

I just mounted them up yesterday.
First off, these suckers mounted really easily (buddy showed me how to use his tire mount/balance machines). They balanced even easier. Two wheels needed 1oz, another 0.75oz, and the third 0.50oz.
Second, holy crap are they an improvement over the 'Kooks. I understand the crazy love people have for these tires now. I have no doubt that the 'Kooks have much more grip for track/autocross. But the MPSS is just so quiet, soft, and comfortable comparatively that I don't even care for a street-driven car.

If you're looking for a good deal on very good summer tires to fit the OEM wheels...
https://www.discounttiredirect.com/buy-tires/michelin-pilot-super-sport/p/34216
Do you have any pics with the 235s?
 

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Discussion Starter · #10 ·
Sorry, no photos handy and the snow tires are on the car now.

I can tell you that it's a little balloon-ey on the 18x7 but if you're going for a more chunky look, this will do it.
 

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235/50r18 Wildpeak A/T Trail are going on right now. We test fit one in the front... They rub just a hair at full lock on the plastic liner. I'll be pulling out the heat gun this Friday and fixing that and lifting come spring, so I'm going to call this a win.
 

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Thanks to this informative thread, I replaced the Pirelli’s that did not last 20000 miles.
I purchase the Bridgestone Potenza 235/45 R18. The tires fit great. Question: if I should need to put on the factory spare, is there any issue?
 

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I just bought a 2019 CX-3 GS with 16 inch wheels/tires and I would like to install 18 inch wheels/tires - is this a good idea or will it create problems?
 

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FACTORY SPARE WHEEL.
[1] It is not recomended to put factory spares on the front of cars as a replacement if you get a puncture.
( Because you should have two good wheels for steering )

[2] Remove the O.E.M wheel from the rear corner.

[3] Replace it with the spare wheel from the boot.

[4] install the rear OEM road wheel on the front on the vehicle.

[5] Place the faulty wheel in the boot.

PLAN "B"
If the factory spare is faulty !
Remove punctured tire and . plug it using a good quality plug kit.
Always carry a portable air pump, a foot pump will do just fine.
It is good to learn how to plug tires by practicing on an old tire from the tire shop first pepper the tread only with holes.
Never remove the nail until you have clearly mark the location of the hole first with an "X"

There are safety issues here, be very carefull. Much worse at night .
Regardless always get help.


X3 Soul red 2 ltr 6 gears
 

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I just bought a 2019 CX-3 GS with 16 inch wheels/tires and I would like to install 18 inch wheels/tires - is this a good idea or will it create problems?
There should be no problem changing the size of the wheels your GS. The GT models come with 18" wheels and 215/50 tires as a factory option. I change between 18" and 17" rims on my GT twice a year because my winter wheels and snow tires are 17's.

You will need to change the aspect ratio from 60 on your 16" tires to 50 on the new 18" rims and this will have an effect on the ride quality, because the shorter sidewall doesn't soak up bumps quite as well. The chart on this post gives all of the compatible tire sizes that will fit on the car using different rims sizes.

You will have to check to be sure you get rims that are compatible with the proper bolt pattern, offset and centre bore size. You could go to Mazda, but their prices are way too high. Most wheel suppliers have the specifications so once you tell them which vehicle they are to be used on they will provide the rims that will fit.
 

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There should be no problem changing the size of the wheels your GS. The GT models come with 18" wheels and 215/50 tires as a factory option. I change between 18" and 17" rims on my GT twice a year because my winter wheels and snow tires are 17's.

You will need to change the aspect ratio from 60 on your 16" tires to 50 on the new 18" rims and this will have an effect on the ride quality, because the shorter sidewall doesn't soak up bumps quite as well. The chart on this post gives all of the compatible tire sizes that will fit on the car using different rims sizes.

You will have to check to be sure you get rims that are compatible with the proper bolt pattern, offset and centre bore size. You could go to Mazda, but their prices are way too high. Most wheel suppliers have the specifications so once you tell them which vehicle they are to be used on they will provide the rims that will fit.
Odometer?

How a Change in Tire Size Affects Speedometer Accuracy

When you change out your tires and wheels for a larger wheel, you always want to respect the overall diameter (OD) of the original tire. A lower profile tire must be placed on a larger wheel to keep the OD close to the same as the tire/wheel combination being replaced. You certainly never more than a 5% difference in OD to the original tire. Too large a variation could impact the gearing and correct operation of the vehicle. Also, any change in the tire OD will give you a false reading of speed and distance on your odometer.

When your vehicle was new, the speedometer was calibrated by the factory according to the exact size of the intended tires. If you change to a taller tire, the circumference of the tire will also be greater. What this means is one rotation of the tire will take you further on your new tires than on your old tires. If the speedometer was never re-calibrated with the new tires, it will register a slower speed than you are travelling. For example, if your tire was 3% taller (still within approved guidelines for plus fitments) the gearing and operation of the vehicle would be fine, however your speedometer would show 60 mph, when in fact you are traveling 63.3 mph.

An easy way to measure your speedometer accuracy it to run a road test. Freeways have mile markers that indicate the length of each mile you are traveling. The safest and most accurate way to execute this test is to have a passenger in the car with a stopwatch. Set your cruise control at 60 mph, and start the stopwatch when you pass the mile marker. It should take you 60 seconds to pass the next mile marker. Repeat the test three or four times to be sure, and average the resulting times. If your average time is off by 3 seconds or more, your speedometer is likely in need of re-calibration. If you have changed out the tire and wheel package, the OD and resulting change in revolutions per mile is likely the cause.
 

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Odometer?

When you change out your tires and wheels for a larger wheel, you always want to respect the overall diameter (OD) of the original tire. A lower profile tire must be placed on a larger wheel to keep the OD close to the same as the tire/wheel combination being replaced. You certainly never more than a 5% difference in OD to the original tire. Too large a variation could impact the gearing and correct operation of the vehicle. Also, any change in the tire OD will give you a false reading of speed and distance on your odometer.
This is why I advised the OP to reduce the aspect ratio when changing to a larger wheel. I also pointed out the chart in this post that gives a lot of great information, most importantly the percentage of difference from the factory tires. This information will give you an idea of the impact on engine revs and speedometer/odometer error. By the way, most manufacturers set the speedometer calibration to read slightly higher than your actual speed.
 

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This is why I advised the OP to reduce the aspect ratio when changing to a larger wheel. I also pointed out the chart in this post that gives a lot of great information, most importantly the percentage of difference from the factory tires. This information will give you an idea of the impact on engine revs and speedometer/odometer error. By the way, most manufacturers set the speedometer calibration to read slightly higher than your actual speed.
Joem1K and Malks.
This is not about looks, its about practicality.

Both of you make some very good points with respect to side wall or aspect ratio ,some of my previouse cars had 60 % side walls the Toyota R.A.V. 4 tires were all tire and not much wheel .
I some times wonder why people want bigger wheels ( that's the metal bit, i mean mental ) as tire share some of the comfort responsibility with the suspension.
Please allow me to to make a comparison between the 225 /55 /18 and the 225/ 50 /18 tires, the difference in side wall height and is very close to an increase of 1/2"
From a practical point of view, I read there are complaint relating to potholes and rim damage.

Until they fix the roads we have to make the best of the worst. provided tires are inflated the the correct P.S.I.

A 55% tire side wall tire contains a greater volume of air than the 50 % tire
Code:
 providing additional comfort .
  A 55% tire  has an additional 1/2" side wall  hight advantage over the 50% tire
this, some what reduces the risk of rim damage ( slowing down also helps )
The slightly bigger change come from when you compare a 225/55/18 with an OEM 215 /50/ 18 tire the 225 /55 is higher by .64 "

Question ~~~ Would the the 225/55 tire side wall bulge when compared to the 225 /50 or the 215/50 tire on a 18"X 7" rim that could be passed off with additional air pressure ?

To be conservative a 225 /50/18 has minor changes and may be the better option.
The result will be a slightly wider an taller tire than 215 /50/18 OEM by .39 " & .19" respectively.

Going to a car show ? the sky is the limit .
 

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ERROR CORRECTION
RE: the Question section above . Kindly delete ( or the 215 /50 tire) which does not belong in that sentence.
 
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