Tire Width vs Rim Width

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I am wondering if any of you can comment on a more esoteric aspect of tire and rim sizing - tire width vs rim width. Yes, there are general guidelines of rim width vs tire width, but for manufacturers, they often list a detailed rim width compatibility for a given tire.

For example, I am considering a 215/50 R17 Continental Viking Contact 7 tire, but my rim width is 6J. According to the Continental spec sheet, this is the minimum acceptable width for a 215 tire (range 6"-7.5"), yet the tire is measured by the manufacturer on a 7j rim. In this case, I have 205/50/17 tires already mounted on the rim, which giev a 218mm contact patch on a 6j rim. Upgrading to a 215 on the same 6j rim gives only a 225mm contact patch. Which begs the question. Is it even worth trying for a 215 tire or should I just stick with 205? Once could achieve the same difference in contact patch (228mm) by upgrading the RIM to a 7j rim and keeping the SAME 205 tires.

Do you guys try to use the manufacturer's measured width (highlighted in yellow on the chart) or are you happy with using any tire on any approved rim width?

continental rim width Screen Shot 2020-10-23 at 12.45.27.png
 

whirlwynds

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I don't know about the rim width, but for me the next size up from a 205/50/17 would be a 215/45/17 to keep the diameter about the same.
Yes. I am actually trying to get close to my
Stock summer diameter of 235/35/19. Thus 215/50/17 is identical.
 
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I am wondering if any of you can comment on a more esoteric aspect of tire and rim sizing - tire width vs rim width. Yes, there are general guidelines of rim width vs tire width, but for manufacturers, they often list a detailed rim width compatibility for a given tire.

For example, I am considering a 215/50 R17 Continental Viking Contact 7 tire, but my rim width is 6J. According to the Continental spec sheet, this is the minimum acceptable width for a 215 tire (range 6"-7.5"), yet the tire is measured by the manufacturer on a 7j rim. In this case, I have 205/50/17 tires already mounted on the rim, which giev a 218mm contact patch on a 6j rim. Upgrading to a 215 on the same 6j rim gives only a 225mm contact patch. Which begs the question. Is it even worth trying for a 215 tire or should I just stick with 205? Once could achieve the same difference in contact patch (228mm) by upgrading the RIM to a 7j rim and keeping the SAME 205 tires.

Do you guys try to use the manufacturer's measured width (highlighted in yellow on the chart) or are you happy with using any tire on any approved rim width?

View attachment 32364

For snow driving and anywhere grip is limited, the narrow rim won't harm. It will smooth out steering inputs some and you're therefor less likely to shock the contact patch such that you lose grip. Also, if you do lose grip and slide towards a curb you're less likely to bend or break the rim as the wider tyre provides more of an air cushion.

In summer you will get sloppier handling, but in winter you don't have the grip to make the tyre move around very much on the rim. I always go for the recommended rim width or half an inch up for summer use, but for winter I'm more likely to go towards the narrow range.
 
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I try when possible, for reduced tire sidewall flex, cooler running and longer life, to use the widest wheel listed for a given tire.
For example, my last 2 tire and wheel combinbations were 295/55/20 Nitto EXO and 295/65/20 Toyo CTs both on 20x10"
wide Fuel Cyclone wheels. The wheels are 86% of the tire section. 295mm = 11.6"
edit; The 265/70/18 take-off's from a 3500 Chev went on 18x9" 1500 6 bolt wheels. Again, 86% tire/wheel ratio.

I like to keep the wheels at least 75% of the tire width.
 
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Whirlwynds,

Something's wrong.

A 205 tire ought to be about 205mm wide on the measuring rim.

Plus it's tread width ought to be about 180mm.

Double plus, tread width doesn't vary with rim width, but section width does - but those values are too wide for section width!

So that chart is all wrong. Let me do some research and I'll post back!

And until I do, here's a tidbit: Within the allowable rim width range, tire performance doesn't change much. Outside that range, it's a different story, but inside the range, rolling resistance, traction, ride, and handling are largely unaffected..
 
Last edited:
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Research done.

That column of values is from ETRTO (European Tyre and Rim Technical Organization) and it is the maximum section width value ANY tire of that size is allowed to have. The data is for car designers so they can make sure there is enough clearance under the fenders. It is NOT real measurements. It is also not tread width nor have anything to do with the contact patch.

So in light of that, your question doesn't make sense.

But here is some advice: The road surface has much, much more grip than snow does, so anything you can do to penetrate the snow layer is beneficial - and that means narrow tread and high pressure.

If you are willing to change wheels, you could use a smaller diameter wheel and an even more narrow tire. See Tire Rack for details on what fits your car.
 

whirlwynds

Thread starter
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7
Qa
For best handling, you want the widest allowable rim for the tire being used. And like Capri said, for snow/winter the skinnier the better at the trade off for dry road grip.
which brings me to my next question. In a climate where it gets cold but rarely snows (Toronto), what width of tire should one be using? 205? 215? or 225?
 
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Qa

which brings me to my next question. In a climate where it gets cold but rarely snows (Toronto), what width of tire should one be using? 205? 215? or 225?
Highly doubt you’ll be able to tell a difference. Tread design and tire compound will matter far more than a 0.787” change in width.
 

whirlwynds

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What vehicle are we talking about here specifically?
2018 golf R. Stock size is 235/35/19 for summers. optional winter sizing most common is 225/40/18 or 225/45/17. but many also use 215/50/17 for exact diameter match or 205/50/17 is recommended by VW
 
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2018 golf R. Stock size is 235/35/19 for summers. optional winter sizing most common is 225/40/18 or 225/45/17. but many also use 215/50/17 for exact diameter match or 205/50/17 is recommended by VW
Looking at TireRack, the only ones they recommend are 225/40/18 and 225/45/17. Since this is for winter, between these two sizes, I'd go with 225/45/17 as it'll give you a bit more pothole protection, plus winter tires should be a bit cheaper in that size. However, you mentioned that your rims are only 6" wide, which is too narrow for that tire size, so you're looking at having to buy new rims.

If you wish to use your existing 17x6 rims (are they really this narrow???) with 205/50/17 tires, just make sure it is the XL version as the regular version has lower load rating index than stock.
 
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I don't like a lot of bulge in the sidewall. Makes the tire slightly less stable at higher speeds. For example, my Nissan Hardbody has 195/75r14 tires on 14x6 wheels. I've run 275/60r15 tires on 15x10 wheels.
 
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