Why 17" vs other bigger sizes

[ATX_Jeeper]

Can I add… if you don’t want to scratch your rims as much, go smaller… I had 20’s on a Dodge Ram… it sucked… rammed those bitches into many curbs… I’m super glad to have 17’s on my JTR.

I’m on -12 with a 4.53 backspace. Not the best shots but what I got.

Ps… I am that bad driver lmao

Off topic but I gotta ask. It looks like you've run both the tires I'm considering. Is there a big difference between the two? Specifically in wet or winter driving and off road?

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[dcmdon]

On both cars and trucks there are reasons of appearance and reasons of function; and from a functional perspective there are engineering trade offs. .

If you care about on-road performance rolling diameter isn't really relevant. What is relevant is brake rotor diameter. When my dad and I used to autocross his RX7 we ran wheels 2 inches smaller than stock with the same low profile tires. This was the smallest that would clear the calibers. It had several advantges. (Remember that an autocross run lasts about 60 seconds so large brakes aren't necessary)

1) the car sits lower, lowering CG and roll center.
2) lighter weight including less unsprung weight, so suspension works better.
3) less rotating mass / flywheel effect.
4) lower gearing, which when you are auto crossing is a good thing.

On something like a jeep, rolling diameter is important. So smaller wheels are usually paired with higher profile tires. This has the obvious advantage of providing cushioning and protection for the rim.

Too small a wheel and along with it small brakes and you compromise brake performance on the road. (A 5000 lb gladiator has smaller brake rotors than my old 3000 lb Subaru)

Too large and you end up with sidewalls that don't work off road.

I realized that 20in wheels with low profile tires are a street only combination. I think that's pretty obvious. And I also think it looks ridiculous. The engineering compromises of a Wrangler or Gladiator are so skewed towards off road performance that to put on 45 series tires on 20s is as ridiculous as putting mudders on a Corvette.

But what if we took a combination that had the same sidewall height as a 37 on a 17 and applied it to a 20 in wheel. We'd now have a 40in tire. We'd have plenty of sidewall for off road use but less sidewall than a 40 on 17s.

It might be a good compromise for someone who wants the approach/departure/breakover angles of 40s with a reasonable degree of on-road manners. Almost nobody drives on road on 40s on 17s because the huge sidewall has so much lateral flex before the tires begin generating later acceleration so the handling is unacceptably sloppy and lethargic.

So maybe if someone wants a street and off road vehicle with 40s, a 20" rim is the answer.

Please realize this is really a mental exercise. I'm keeping 17s on my Jeep because I'm not going any larger than 35s. But if you go bigger and want to strike a more street oriented compromise, maybe an 18 is a decent idea.

 

[rezar1]

My plan is to go with 37" tires. 40" would be too much. I am assuming from what everyone has mentioned that 17" will work?

I just need to figure out the offset/backspace so that the tires are not sticking out too much. I want to be flush to the fenders or at most sticking out by 1". Not more.

I forgot to mention that I am going with Clayton 3.5" lift and falcon shocks.

 

[Tstrausburg]

My plan is to go with 37" tires. 40" would be too much. I am assuming from what everyone has mentioned that 17" will work?

I just need to figure out the offset/backspace so that the tires are not sticking out too much. I want to be flush to the fenders or at most sticking out by 1". Not more.

I recommend using the link that Fouts sent: https://tiresize.com/wheel-offset-calculator/

This will let you see the difference is stock (under the fender) and a wheels with different backspacing. I have noticed that a lot of lifts want a minimum of 4.5" backspacing to reduce rubbing of components. This is true for @clayton as well (same lift I am looking at). They are very responsive on this forum. I recommend getting their input as well.

I went with the Icon Rebounds which have a 4.5" backspace (-6mm offset) and they poke about 1.5" to 2". It does not look obnoxious in my opinion....but everyone has their own. I should note that I'm currently only my stock 285's (33's) so your "poke" would be a little different.

If you truly don't want any tire sticking out, I think AEV's wheels are designed to keep them tucked under. https://www.quadratec.com/p/aev/pintler-wheel-wrangler-jl

 

[antwon412]

My personal rule of thumb is no smaller than 50% wheel size.

So, 35” tire, around a 17” wheel

37s, around a 17-18”



Its a good starting point at least.

 

[Mjolnir]

I think you guys are oversimplifying the OP's question.

If he's putting 40s on it, then a 18 or 19 will leave plenty of sidewall.

Or is more always better? If so, then why not 15s or 16s?

I think its about a balance between on-road and off road performance.
For most people with tires between 11 and 13 inches (roughly 275 to 315 metric and 32-33 inches tall) and a 70 series aspect ratio a 17 makes sense.

But if you are running 40s then you would have plenty of sidewall even with a 19.

A guy I know has an overland with 18s. He put a set of Goodyear 285/75-18s on it and it works well. Lots of sidewall in a stock width tire that is about 35" tall.

Its funny how times change. Wheels continue to get larger. Look at an old CJ and its 15" wheels or even an early JK with 16s. 17 just happens to be the sweet spot. For now.

Well OP stated 37's, not 40's so that is irrelevant. If you are offroading then more tends to be better. anything less than 17 won't fit due to calipers or you would see those as options.

Oversimplifying is absolutely ok in this situation. He asked why people recommend 17's.

- Looks better in the eyes of most people
- More sidewall for offroading and airing down
- Highway ride is better, more often than not, vs a 22" rim.

Technical details? Sure many can go into that but to the question "why is this recommended", why not just state the big reasons and be done with it?

 

[Guns_N_Rosaries]

Here's what happens when you big wheels with normal tires, vs normal wheels with big tires:



Spoiler: The same thing happens with the new tire a couple of minutes later.

 

[cannonFodder]

There's quite a few 40" tires on 17" wheels around me, so it was weird to read a lot of the apparently uninformed opinions.

 

[CerOf]

Here's what happens when you big wheels with normal tires, vs normal wheels with big tires:



Spoiler: The same thing happens with the new tire a couple of minutes later.

That pretty much sums it up

 

[Zissou]

More sidewall to confirm to the terrain. Less chance to lose a bead or shred a tire. Protects the wheel better

think about a BMW and it’s low profile tires. Now think about a Camry, same size tire, but smaller rim. There is more rubber on Camry . Less chance to trash the rim or tire in the Camry.

Yup, worrying about that sucks lol

I'd be running 18's on my M2 if I could. 19's are the smallest wheel that can clear the brakes.

And I'd run 16's on the Jeep if I could. Smaller wheel is always my preference.

This is less of a concern for the Jeep since it has a ton of options, but generally I pick tire & tire size first, then pick a wheel size that works for the tire I want.

 

[rezar1]

It looks like -12mm might be little bit more than I want based on the picture as well as the calculator. I most likely will have to go with 0MM or slightly positive offset which rules out the wheel I was looking at since it's only available with -12mm.

For tire I am looking at 37/12.5/17s

 

[DirkG]

There's quite a few 40" tires on 17" wheels around me, so it was weird to read a lot of the apparently uninformed opinions.

BEEFY. Love it. If I recall @cannonFodder, you bought your rig with 22's and I think your profile pic still shows that. What's been your experience going from 22's to 17's?

 

[NC_Overland]

I’m running 30” wheels so I don’t have to air down when I drive on the beach.

 

[shrinkhead]

My plan is to go with 37" tires. 40" would be too much. I am assuming from what everyone has mentioned that 17" will work?

I just need to figure out the offset/backspace so that the tires are not sticking out too much. I want to be flush to the fenders or at most sticking out by 1". Not more.

I forgot to mention that I am going with Clayton 3.5" lift and falcon shocks.

I have the same backspace and offset with my FUEL COVERTs.You need the backspace for clearence with 37s and stock fenders and they will stick out about an inch for 12.5 wide tire on a 17x9 rim. Also do you have your Falcon shocks already? I ordered mine in July of last year and still no luck.

 

[rezar1]

I have the same backspace and offset with my FUEL COVERTs.You need the backspace for clearence with 37s and stock fenders and they will stick out about an inch for 12.5 wide tire on a 17x9 rim. Also do you have your Falcon shocks already? I ordered mine in July of last year and still no luck.

Are you referring to -12mm/4.53 backspace?

Yes on the Falcons. I got very lucky and I think I got the last set. The shop that I got it from called TeraFlex and they found one. The shop could not believe it either as they thought it will be backordered for months. While I wanted the aDapt, I ended up with e-adjust. I figured I can update the electronics later to aDapt.

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