how about fitting 275/45/20? on the original rim?

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CX9 2017
I have been looking for some new tires to replace the terrible bridgestone ecopias, so as i have already written about it ive been looking for a good performace tyre . seems in my country the 255 size isnt common and its expensive and with no good options. The good options come with 275/45/20 size. any experience on this size to be fit on the original 20 rim? the option im looking at is the Good Year asymmetric 3 SUV.
 

sm1ke

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I wouldn't do it. According to this reference, 255 is considered the maximum width for an 8.5" wide rim. Of course, I wouldn't consider this to be written in stone, but just based on how 255 looks on the OEM wheel, I don't think I'd want to go any wider.

How about a 245/50/20 or a 235/55/20 tire? Do you have more options in those sizes?

EDIT: Another option would be getting new rims that are 10" wide.. 😉
 
a 275/45R20 is permitted on a 8.5" rim, thats the narrowest per ETRTO manuals.
A 275/40R20 needs at least a 9.0" wide rim

So, you can use a 275/45R20 on our stock wheels, and the diameter is also pretty much the same as the stock 255/50R20's. Only question will be with the wider tread width and section width, will it contact the strut.
I have been thinking to go to this same size to improve the looks more than anything. Although the stock Ecopias, since they are targeting ride, noise, and fuel economy (rolling resistance) are on the narrow side for tread width and tire design standards (there is a window), so a more main stream 255/50R20 will look better/wider, not requiring the need to go up to a 275, so I am still undecided.

Pay attention to tread widths as well as section widths of any tire you look at, as the tread width can vary from tire to tire, yet the section width (widest part) has to be within standards. So you can have 2 tires with identical section width, yet one looks wider and has a wider footprint because the tread width is wider. Not all companies provide the tread width in their specs, but you can contact them to find out.

Goodyear Asym 3's are excellent performance tires. They ride very nice for a high performance tire, are quiet, and have tremendous dry and wet grip. But they are HIGH PEFORMANCE tires, unlike the Ecopias that are OE on our CX9's, so be aware other performances will be traded-off.
 
BTW, our OE 20" wheels are on the wider side, at 8.5" Nominal rim width for a 255/50R20 is 8.0".
Mazda engineers knew what they were doing, once they selected the tire size, they specd a wider rim to help "tighten/stretch" the "sidewalls" by mounting the tire on an allowable wider rim, which in turn improves most handling performances. We are lucky, most other vehicles with our same or similar tire size are on a 8.0" wide rim.
 
Gatuno, let us know if you decide to go the 275/45R20 route, I would like to see pics and know if you have any clearance issues (Im guessing not - Ill have to measure the current gap from the stock 255's to the strut tower.).
 

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Gatuno, let us know if you decide to go the 275/45R20 route, I would like to see pics and know if you have any clearance issues (Im guessing not - Ill have to measure the current gap from the stock 255's to the strut tower.).
A 20 mm increase in width (10mm on both sides) will clear just fine based on this photo I took when I was shopping for summer wheels. I didn't measure the exact distance, but there looks to be approximately 1" of clearance with the OEM Ecopias.

IMG_20180902_115753.jpg
 
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CX9 2017
Hello all and thanks for the comments all very useful and helped me make may decision so.... ,

I got some news, this morning I got the asymmetric 3 SUV 275/45/20 s on my stock rims, tried them out on the front first to see if there was enough space, there is a lot of space down there so no problem on that side, after having all checked we put all the 4 new tires into the rims and balanced them.
First impressions:
a) There is a little more noise than with he Ecopias on smooth surfaces .
b) Instantly you can feel the steering faster ( i wasnt expecting that ) turn in is faster although the tire is wider
c) noise is down when driving on rough pavement, much much better now , this is where the Ecopias really sucked, vibration was all inside the cabin while driving on rough pavement ( not bad pavement just rough)
d) much smoother specially over potholes and as said before rough pavement.
e) Looks ; even though this is the minimum rim width for this size of tire it looks very flat ( squared) on the side walls , i was afraid it would look with a belly ( something that happens when u use a fat tire on a slim rim) but it doesn't, it just looks great. also when looking the CX9 from the back you can tell the tire looks wider and better than the Ecopias.
f) stickier? yes much stickier although i will let a few hundred miles for the tyre to adapt before putting it into their limits in cornering.

Yes , of course I'm thinking about putting new 10 inch wide rims LOL. !!!
 

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Awesome, I new techinically they would work, and glad to see plenty of clearance. As I mentioned, there is a window within tire size standards, and some can be on the narrow end, or wide end for the section width (which you described as flat or belly for the sidewall profile) and also the tread arc width, which there is no standard for, and can vary depending on the tire design. The Goodyear Asym 3 is a narrower design, so probably not much wider in section width than the OE 255, so its a squarer looking tire on our relatively "narrow for this size" wheel. But the tread arc width is wider than the Ecopias since its a 275, so its a win!
Thanks for the feedback and pics.
yes, the tire will "relax" and break in, about 100 - 500 miles, as will mold release wear away from the tread surface if any was present, so handling will only improve. Thats the benefit of a UHP tire vs the low RR tire like the Ecopias. If you have only summer climate, then you are set!
 
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CX9 2017
Awesome, I new techinically they would work, and glad to see plenty of clearance. As I mentioned, there is a window within tire size standards, and some can be on the narrow end, or wide end for the section width (which you described as flat or belly for the sidewall profile) and also the tread arc width, which there is no standard for, and can vary depending on the tire design. The Goodyear Asym 3 is a narrower design, so probably not much wider in section width than the OE 255, so its a squarer looking tire on our relatively "narrow for this size" wheel. But the tread arc width is wider than the Ecopias since its a 275, so its a win!
Thanks for the feedback and pics.
yes, the tire will "relax" and break in, about 100 - 500 miles, as will mold release wear away from the tread surface if any was present, so handling will only improve. Thats the benefit of a UHP tire vs the low RR tire like the Ecopias. If you have only summer climate, then you are set!
This is a all summer weather the year long, but 60 miles west you have the andes where u can climb all the way to 17000 feet from 0 feet ( where i live) sea side , the weather changes drastically temperature goes from 30 C to 5 C in a cpl of hours drive and you can go from dry to rainy conditions. This is where the CX9 excels, the mountain roads with the family . No other suv near this price comes close . want something close? go Q7 upwards.
Here something a wrote about the cx9 when i bought it .

 

sm1ke

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Gatuno, that was a great read, I'm not sure how I missed it. I, for one, would love to see some footage of the drive up to the mountains and back, maybe if you have a dashcam or if you can ask you copilot to record some of the more fun twists and turns. I live in the Prairies and it's generally quite flat around here, but it was fun to drive the CX-9 around Calgary, where there's a little more variation in elevation and freeways with higher speed limits.
 
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