Talk me out of 215/85/16s

[Brendon Holt]

Like the title says... I'm intrigued because they are a similar sized outer diameter to the popular 245/75/16 but, I kinda like the small/skinny tire look/function, although they may be a bit too skinny. 235/75/16s are another option but they're a half inch smaller in outer diameter.

Am planning on an OME lift when I do change tires so I should have ample room for stuffing any of these under the Jeep. I'm not looking to regear so I don't really wanna surpass that 31"(ish) outer diameter number and any rolling resistance I can shave off by using a narrower tire helps too.

 

[lfhoward]

From TireSize.com: 215/75R16 tires have a diameter of 28.7", a section width of 8.5", and a wheel diameter of 16". The circumference is 90.1" and they have 703 revolutions per mile. Generally they are approved to be mounted on 5.5-7" wide wheels. (Emphasis mine)

The stock Liberty wheel is 7 inches wide, so you would be right at the edge of too narrow. This means you probably couldn't air down much while off-road because you'd be in danger of losing the bead and your tire going completely flat. I don't think I would do it.

 

[Brendon Holt]

From TireSize.com: 215/75R16 tires have a diameter of 28.7", a section width of 8.5", and a wheel diameter of 16". The circumference is 90.1" and they have 703 revolutions per mile. Generally they are approved to be mounted on 5.5-7" wide wheels. (Emphasis mine)

The stock Liberty wheel is 7 inches wide, so you would be right at the edge of too narrow. This means you probably couldn't air down much while off-road because you'd be in danger of losing the bead and your tire going completely flat. I don't think I would do it.

Yeah that's another issue I'm having with them 6" wheels are hard to come by. Granted I'm not sure how much I'd be airing down with the driving I plan on doing but it's better to have the option than not. Honestly my ideal tire size would be to run 235/85/16 but that's asking for regearing and a lot more work to get them to fit nicely into the wheel wells.

 

[lfhoward]

True. I considered 235/85R16's when I got tires this fall. I ended up going with 245/75R16 for more traction (larger contact patch with the ground). I have a 4" lift (more like 3.5" now) so rubbing isn't an issue. I do wish I had the $$$ to regear though. There is a tangible loss of power and efficiency going to this size, although it isn't a complete deal breaker. I will say that I can tell my load range E KO2's are heavier than the load range C Duratracs they replaced (same size), and the extra weight makes even more of a difference. Regearing is definitely in the plan at some point.

 

[Brendon Holt]

True. I considered 235/85R16's when I got tires this fall. I ended up going with 245/75R16 for more traction (larger contact patch with the ground). I have a 4" lift (more like 3.5" now) so rubbing isn't an issue. I do wish I had the $$$ to regear though. There is a tangible loss of power and efficiency going to this size, although it isn't a complete deal breaker. I will say that I can tell my load range E KO2's are heavier than the load range C Duratracs they replaced (same size), and the extra weight makes even more of a difference. Regearing is definitely in the plan at some point.

I know the argument for a narrower tire (among others like rolling resistance and reduced weight and all that) is that when it comes to traction a narrower tire focuses the weight of the vehicle onto a smaller area which increases the amount force per unit of area pressing into the surface you're trying to grip. So that in some ways the narrower tire will grip "harder" than a wider tire in the same circumstance. Now, how much that actually cashes out in real life is something I'd like to see a more thorough test on.

I will say one strong argument for going with the usual 245/75/16s is you can run them on Moabs and that's a damn good argument in itself

 

[tommudd]

Look at tire weight and how many ply they are as well, most of those are 8-10 ply and heavy

 

[Brendon Holt]

Look at tire weight and how many ply they are as well, most of those are 8-10 ply and heavy

They're also just generally more expensive than a 245/75/16. More points against.

 

[tommudd]

Never did like narrow tires , I run 265-70-16s on my DD , fit perfect on Moabs
as far as 245-75-16s fitting on Moabs , ues they do but tread is not wide enough in my opinion for an 8 inch wheel
the only reason Jeep did it was due to advertising, they wanted to advertise a 8 inch wheel on the Rubicon, they wanted a 31 inch tall tire and wanted the MTR, only one available was the 245-75-16 so they ran with it

 

[Brendon Holt]

Never did like narrow tires , I run 265-70-16s on my DD , fit perfect on Moabs
as far as 245-75-16s fitting on Moabs , ues they do but tread is not wide enough in my opinion for an 8 inch wheel
the only reason Jeep did it was due to advertising, they wanted to advertise a 8 inch wheel on the Rubicon, they wanted a 31 inch tall tire and wanted the MTR, only one available was the 245-75-16 so they ran with it

Yeah, you still have the risk of popping beads airing down a 245 on an 8" wheel right? What's the weight difference between the 245 and the 265?

 

[Brendon Holt]

You must be registered for see images attach

I wouldn't mind finding a set of these stock wheels to stay with a 16x7. I've never minded the look of those fat 5 spokes. Not a Moab but still decent. Oh, picture credit: I stole this from jrs05kj over at Lost Jeeps.

 

[lfhoward]

You can find Liberty wheels near you that don’t cost a lot on http://www.car-part.com. Recycle and reuse!

That’s how I got my 5th matching wheel to replace the doughnut spare. For $69 I even got a free working tire pressure sensor on it.

 

[Michael Maxwell]

Is anyone here running 215’s on stock rims?
I’m curious if there is an mpg advantage to doing it. Rarely off road, my gas KJ is a commuter with stock 225’s.

 

[lfhoward]

215-what’s?

 

[Brendon Holt]

Is anyone here running 215’s on stock rims?
I’m curious if there is an mpg advantage to doing it. Rarely off road, my gas KJ is a commuter with stock 225’s.

I think some of them came with 215s on the stock wheels (215/75/16?). That said, a 215 is kinda the limit for how narrow of a tire you can run on a 7" wheel from what I've gathered. I'm not sure how much you'd save in weight/rolling resistance going from a 225 to 215 but I would venture a guess that it won't be much (guessing you want to keep outside diameter the same since it's just a commuter). Maybe someone else can chime in with different info. The KJ is just, well, not awesome for fuel economy. No matter what it's still like throwing a very heavy brick into a hurricane at the end of the day.

 

[tommudd]

Is anyone here running 215’s on stock rims?
I’m curious if there is an mpg advantage to doing it. Rarely off road, my gas KJ is a commuter with stock 225’s.

You may get 1 or 2 tenths of a mile more per gallon , not worth it

 

[tommudd]

I always have to laugh when people think KJs do not get get good gas mileage

 

[Brendon Holt]

I always have to laugh when people think KJs do not get get good gas mileage

*Shrug* I mean there's an entire thread dedicated to ****** MPGs here so I think your 20+ MPG runs are more the anomaly than the norm. I get about 14-15 around town and I've MAYBE pulled 19 on the highway. To be fair it's better than my old WJ but still not what most people would call awesome. But, you don't buy a Jeep to sip gas, so...

 

[tommudd]

Keep your KJ in good shape maintenance wise, air pressure in tires checked on regular basis etc and they will get good gas mileage
I drive over 95 miles a day over hilly, twisty ( think roads that were built following a snake ) and get decent mileage everyday and that is driving at or over the speed limit a little
Many baby/granny drive their KJs which they hate, 3.7s like to be run
Plus these were not built like the sissy SUV's like Rav 4s, the little Hondas etc
so of course do not get 30 MPGs , but they do good for the way they were built etc
As far as mine being an "anomaly " I have 3, 2 lifted , well actully all 3 are above stock height and running larger tires and all get good mileage, plus I know others who do as well.
Soooooooooooooooo, we're all an " anomaly " ?

 

[Brendon Holt]

Keep your KJ in good shape maintenance wise, air pressure in tires checked on regular basis etc and they will get good gas mileage
I drive over 95 miles a day over hilly, twisty ( think roads that were built following a snake ) and get decent mileage everyday and that is driving at or over the speed limit a little
Many baby/granny drive their KJs which they hate, 3.7s like to be run
Plus these were not built like the sissy SUV's like Rav 4s, the little Hondas etc
so of course do not get 30 MPGs , but they do good for the way they were built etc
As far as mine being an "anomaly " I have 3, 2 lifted , well actully all 3 are above stock height and running larger tires and all get good mileage, plus I know others who do as well.
Soooooooooooooooo, we're all an " anomaly " ?

I have kept up on all routine maintenance on mine (or at least have since it became mine), and run my 245/70/16s at 35psi. Should I run more air?

When you say you get decent mileage every day from that drive what numbers are we talking about?

I'll be honest I'm probably in the granny driving crowd. I've read your comments on driving them with more "spirit" and have tried to implement it but I always fall back into the same grandma style driving habits. If I pull off from a light or stop sign I don't think my RPMs ever get above 3k. When you say they like to be run what are we talking about?

I'm still gonna go with those numbers being the exception just based off something like Fuelly where we can get a larger pool of data and the average from that comes to about 16-17MPG average (which, by most standards isn't great fuel economy but like you said it's not a Rav4). Also in your defense they probably don't take care of their KJs they way you and your friends do.

 

[lfhoward]

Tom’s KJ’s with larger tires are regeared to 4.10. When he says he gets good mileage it’s no joke. I rode with him once and he was getting 24 mpg on a back road in northern Ohio according to his Scangauge. He said he can get 21-22 on the interstate at 80 mph. His KJ was built up with skids, rock sliders, ARB bumper, etc. so it was not stripped down to make it light.

Regearing with larger diameter tires is really the key. I’m running 31’s and average 12 mpg around town and 17 on the highway with stock 3.73 gears. Have researched regearing and would love to, but still saving up the $$$.