Wheel/tire diameter discussion

[white03]

I've been reading everything I can in this forum trying to learn about wheels and tires, to get informed on making a purchase decision.

And I want to publicly acknowledge YowStinger for being patient and very helpful in private conversations answering all my questions!!! If I ever get to Ottawa CN I going to buy him the lunch of his choice!!

What I'm wondering now concerns wheel diameter and tire size: how the two effect each other

So I think I'm correct that our OEM 19" wheels and tires are jointly a 26" diameter, and I have the chart that shows what tires can be put on 19" wheels and stay with a 26" diameter. And I have the chart for 20" wheels and tires that will maintain a 26" wheel/tire diameter.

My question for discussion is "what happens to tire size and vehicle stance when going from 19' wheels to 20" wheels"??

Logically, at least to my current way of thinking, if wanting to stay at 26" total diameter and increasing wheel size by 1", then overall tire sidewall has to decrease by 1"...is this correct??

Thank you all for helping rookies!!

 

[DrMario86]

There's a good calculator to match the revolutions per mile so you don't goof your speedometer.

Tire Size Calculator

The best tire size calculator. Use our tire size calculator to find tire size specs and suggested tire sizes. Then check prices for all available tire sizes.

tiresize.com

The rear 255/35/19 are 775 rev/mi. To match that, 255/30/20 comes out exactly even. Lots of playing here if you wanna get clever with the size changes.

 

[MerlintheMad]

Logically, at least to my current way of thinking, if wanting to stay at 26" total diameter and increasing wheel size by 1", then overall tire sidewall has to decrease by 1"...is this correct??

1/2" less sidewall equals 1" smaller OD.

 

[white03]

Roger that Merlin, another way of saying the same thing I said, or meant.

So if that's the case, then 1/2" less sidewall = more susceptibility to damaging the wheels .... right??

And if that's the case then maybe, when going to 20" wheels, selecting a tire size to give a to 27" overall diameter is a good idea....???????

 

[MerlintheMad]

I have no interest in messing with bigger wheels!? 19s are already big enough. I used to mock drivers with enormous wheels and "rubber band tires". Now I am one. But I'm not going to even more extremes. I've gotten used to the look over a long time. It's not my favorite look: that would be a proper sidewall, a la 60s and into the 70s style, with a nice, deeply inset mag wheel. I will never get used to the ludicrous combination of a rubber band tire on an off-road vehicle or pickup truck.

 

[Buklau]

Has anyone run 245/40/20 and 275/35/20 on AWD before? I want to go 20s but want a bit more sidewall so I don’t destroy my wheels on potholes.

 

[DrMario86]

Has anyone run 245/40/20 and 275/35/20 on AWD before? I want to go 20s but want a bit more sidewall so I don’t destroy my wheels on potholes.

Can't say how much it would annoy you but just for the numbers, here's the comparo for the rear.


The fronts a little more different at +6.5% on overall size and speedo error. Fixable if you care but not the easiest. I'm not super knowledgeable on rim fitment but going up 2-2.5" on the rear is pretty chonky.

 

[Marylandkiastingergt]

Roger that Merlin, another way of saying the same thing I said, or meant.

So if that's the case, then 1/2" less sidewall = more susceptibility to damaging the wheels .... right??

And if that's the case then maybe, when going to 20" wheels, selecting a tire size to give a to 27" overall diameter is a good idea....???????

I switched to a square setup 20x9 with 38 offset Niche Milano and 245/35/20 tires which are slighter larger diameter than stock, but only about a mph difference at highway speeds. I have not experienced any issues with pot holes etc... with the change. There were a couple benefits that I feel make the upgrade worth the investment: 1)The cornering and steering feel from the wider track at the front vs stock and the slightly smaller sidewall does contribute as well to the response. 2)Tire Rotation: I know many owners run staggered setups and they look great, but I drive too many miles and so tire rotation is more important than looks to my situation. I was getting maybe 25,000 miles from a set of tires and at $250 each it was getting expensive. It was a good way to explain to my wife why the tire and rim investment was needed 3) Looks: With the slightly larger wheels/tires and offset than stock, it fills the wheel wells better and gives a nice flush look and closed part of the wheel gap. BTW I haven’t seen any issues with traction even though I own a RWD and the rear tires are slightly more narrow than stock. I mean if you want to break the tires loose the car will oblige whether it’s a 245 or 285 width with enough throttle. If you want a nice upgrade to the looks and driving experience I highly recommend the change! Best of luck on your decision

 

[MerlintheMad]

I switched to a square setup 20x9 with 38 offset Niche Milano and 245/35/20 tires which are slighter larger diameter than stock, but only about a mph difference at highway speeds. I have not experienced any issues with pot holes etc... with the change. There were a couple benefits that I feel make the upgrade worth the investment: 1)The cornering and steering feel from the wider track at the front vs stock and the slightly smaller sidewall does contribute as well to the response. 2)Tire Rotation: I know many owners run staggered setups and they look great, but I drive too many miles and so tire rotation is more important than looks to my situation. I was getting maybe 25,000 miles from a set of tires and at $250 each it was getting expensive. It was a good way to explain to my wife why the tire and rim investment was needed 3) Looks: With the slightly larger wheels/tires and offset than stock, it fills the wheel wells better and gives a nice flush look and closed part of the wheel gap. BTW I haven’t seen any issues with traction even though I own a RWD and the rear tires are slightly more narrow than stock. I mean if you want to break the tires loose the car will oblige whether it’s a 245 or 285 width with enough throttle. If you want a nice upgrade to the looks and driving experience I highly recommend the change! Best of luck on your decision

Are you going to flash some pics of your wheels? It's quite popular on here to do that, you know.

 

[Marylandkiastingergt]

Here is a picture of the wheels sorry Merlin