35s and the skinny tire - JeepForum.com
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post #1 of 23 Old 05-06-2019, 02:13 PM Thread Starter
coloradoman
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35s and the skinny tire

So I understand you need a lift for 35s on a rubicon. What kind of lift if any would you need for https://www.ebay.com/itm/35X10-50R17...EAAOSwEVZcwmIx

These are only 10.5 inches wide, so much smaller than the normal 12.5 inches on 35s. I am wondering if you need lesser modifications to fit this tire.

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post #2 of 23 Old 05-06-2019, 09:49 PM
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Height wise it won’t matter. The width primarily affects the backspacing required which is really a function of the wheels.

So no, this isn’t the cheap way to run 35’s that you were hoping for.

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post #3 of 23 Old 05-07-2019, 07:57 AM Thread Starter
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Originally Posted by Prot View Post
Height wise it won’t matter. The width primarily affects the backspacing required which is really a function of the wheels.

So no, this isn’t the cheap way to run 35’s that you were hoping for.
Yeah I was thinking this would be the response. Hey at least you might get some better mpgs, since they weigh less and have less air resistance. I wonder how good they actually are as far as their snow and on road performance. I am thinking their off road performance is probably better than just the A/Ts
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post #4 of 23 Old 05-07-2019, 12:33 PM Thread Starter
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So this tire is almost an inch more narrow than the stock rubicon tires. I think it is possible to do 35s without a lift with these tires and no rubbing off road.
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post #5 of 23 Old 05-07-2019, 01:49 PM
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if you have a JL RUBICON--a lift is not required for 35" tires--

General width has no effect on it--as long as you use the proper WHEELS/BACKSPACE

W.E.

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post #6 of 23 Old 05-07-2019, 01:57 PM
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Stock Rubicon tires are 285/70R17 or roughly the equivalent of a 33x11 tire (32.7" diameter). The tires you linked to are 34.7" diameter, so an additional two inches over stock but also slightly narrower, so a tad more room to the shoulder/sidewall when flexing.

Quote:
I think it is possible to do 35s without a lift with these tires and no rubbing off road.
You're likely correct. Throw on a set and let us know how it works for you -- pics are appreciated as well.

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post #7 of 23 Old 05-09-2019, 11:00 AM Thread Starter
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Originally Posted by mukluk View Post
Stock Rubicon tires are 285/70R17 or roughly the equivalent of a 33x11 tire (32.7" diameter). The tires you linked to are 34.7" diameter, so an additional two inches over stock but also slightly narrower, so a tad more room to the shoulder/sidewall when flexing.


You're likely correct. Throw on a set and let us know how it works for you -- pics are appreciated as well.
I would if I had some extra cash to burn lol. Its just plans for the future like maybe a year from now. From what I've seen in this video (this guy has 33s stock tire)

It looks like it would be tight but I bet it would fit. It would be an inch taller on both sides of the wheel (combined 2 inches taller) but a half inch less wide, so a quarter inch less wide on the inside and outside of the rim.

In this video, the guy really only has a finger width of space at full articulation with sway bar discconnected. I think these 35s would probably take away about 3/4s of an inch of that finger gap so you might have some slight rubbing at full articulation, maybe only a 1/4 inch rubbing into the top of that liner in the front and back.
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post #8 of 23 Old 05-10-2019, 09:08 AM Thread Starter
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There was an article by Scott Brady (the guy who did the Patriot testing) that talked about off-road performance of tires. Here's the section on the pro's and con's of taller narrower tires:

ps. sorry for blowing up the thread

====

Understanding Off-highway Tire Performance:

Important note: For the sake of the following details, assume that the test vehicle is 5,000 lbs., and a narrow tire would be considered a 33x10.5 R15, and a wide tire would be considered a 33x12.5 R15, both run at 15psi for trail use.

The benefits of a narrow tire:

The Argument: A tall, narrow tire is a better choice for all off-highway surface conditions with the exception of soft sand, snow and soft mud that's depth exceeds 110% of the vehicles minimum ground clearance. Here is the explanation.

• Contact Pressure: Contact pressure is expressed as the vehicles curb weight distributed over the contact surface of four tires. The contract pressure is not equal to all four tire road surface contact points as the vehicles weight is not perfectly distributed. To ease the description, let's assume that the test vehicle weights 5,000 lbs and has a perfect weight distribution. Each of the vehicles four tires would be creating 1,250 lbs. of vertical pressure on the terrain. Let's assume for the sake of this example that the vehicles tires are 10” wide, where the load and tire pressure results in a total surface area of 30 sq. inches. The total pressure per square inch (without equating the secant) would equal 40 lbs.

Off-highway effects of contact pressure:

Deformation- On a smooth surface (like concrete), a tire gains most of its traction by adhesion. On an irregular surface like granite and boulders, a tires contact patch will deform as a result of vertical pressure. The wider the tire, the less the rubber will deform to the surface irregularity given the same vertical pressure. The greater the deformation, the greater the tires resistance to shearing forces (spinning). This is the strongest argument to using a narrower tire.

Real world example: When climbing a ledge with a jagged surface, the narrower tire will wrap the protrusions with more contact due to the increased deformation depth. The wider tire will rest on the surface of the protrusions and will have a greater chance of spinning (shearing).

Mechanical Keying: This is the second critical benefit of a narrower tire. As the vertical load increases, so does the compression and flexing of the tires tread and rubber to the surface protrusion. A narrower tire generates greater vertical load on the rubber and the tread, increasing tread compression in conformance to the surface irregularity. A wider tire in contact with more surface conforms less, and will shear sooner than a narrow tire.

Adhesion- On a flat surface, the adhesion rate of a narrow tire and wide tire are the same, as the wider tire makes more contact (friction area), but the narrow tire generates more pressure (vertical load force). On a highly irregular surface, the higher vertical load force of the narrow tire becomes an advantage, increasing molecular bonding between the tires rubber and trail surface. That bonding becomes so great that either the vehicle moves forward, the tire tears leaving rubber on the surface, or the trail surface breaks away.

Typical Questions:

What is the limit of a narrow tires effectiveness? Tire load capacity and rubber tearing. At some point the tire becomes so narrow and the contact pressure so high that the tires rubber molecular bonding cannot sustain the tearing load created by the bonding and mechanical keying to the surface. Remember, the width of a train rail cars wheel is only 4”, and they have incredible traction on a very smooth surface due to the intense vertical load force.

Why do race cars use wide tires? Lateral stability and cooling. Performance cars have wide tires for handling performance not acceleration. A wider tire exhibits less "roll-in" or deflection which affects tire camber and handling. Performance vehicles also drive at high speeds, which generate heat. A wider tire has a greater surface area to dissipate heat (generated from cornering and acceleration forces) at speed. Smooth performance tires rely on the highly tactile track surface with allows for exceptional adhesion.

• Rolling Resistance: A narrow tire presents less rolling resistance on improved surfaces, increasing fuel economy and performance.

• Frontal Resistance: This is another key benefit of using a narrow tire. When driving through mud, snow and sand a narrow tire presents less surface area to the medium. A narrow tire will cut easier through mud, snow and sand than a wide one (due to resistance). The best example of this is when turning in sand. When the front tires turn, they present a wider surface to the sand. You can feel speed reduce immediately when a turn is initiated because of the resistance.

• Rotating Mass: A narrower tire weighs less than a wider one of the same height. The difference in weight between a 33x10.5 and 33x12.5 is about 5 pounds, coupled with the narrower, lighter wheel, the affect on rotating mass is significant. A lighter tire and wheel is easier to accelerate and stop.

• Size Fitment: All things being equal, a narrower tire is almost always easier to fit with less fender trimming and total suspension lift that a wider tire of the same height. Wider tires affect turning circle, compression travel (which needs to be limited by lowering the bumpstops, etc.).

Practical Application: I find a good rule is to use as tall a tire as possible with the same section width as the widest tire available from the factory for that particular model. That way the tire will compress into the wheelwell designed for that width, without rubbing due to width. Example: I was able to fit my Tacoma with a 33.4”x10.5” tire with only a 1 ¾” lift. A 33x12.5” tire would require additional trimming, less wheel offset and lowered bumpstops.

• Weight: Without making this an article about suspension, one of the jobs of a properly engineered suspension is to control the cycling of unsprung weight, which is comprised of the axles (control arms, knuckles, etc. in an IFS), tires and wheels. The lighter those assembly's are, the easier it is for the suspension to control it, improving performance.

• Airing Down: This is another critical concept highlighting the advantage of a narrower tire.

As quoted from Sahara Overland, a Route and Planning Guide by Chris Scott (2004, ISBN: 1-873756-76-3):
"...Note that it's the diameter or height of the tyres that makes the difference in sand, and not, as many imagine the width... For the desert, you want tyres with a high aspect ratio of around 80 because this represents a taller sidewall so corresponds to added ground clearance when firm, and a longer contact area when deflated"

Traction in soft surfaces: It is a common misconception that airing down a tire for off-road traction only makes the tire contact patch wider. That is not the case. In fact, only 20% of the increased contact comes from the width. 80% of the increased contact patch comes from the tread patch becoming longer. A tall, narrow tire allows for a very long contact patch when aired down. That, coupled with the minimal frontal resistance (area), negates much of the downside to narrow tires in flotation situations. The taller tire allows for a long contact patch and still maintains good ground clearance.

Traction on rocky trails: Another common misconception is that when airing down it is the increased amount of tire on the rock (more contact patch), that allows better traction. It is not the contact patch that creates better traction, but the tires ability to conform to the surface irregularities (deformation and mechanical keying). When an aired down tire comes in contact with a rock on the trail, the tires tread collapses under the vertical and horizontal forces, causing the tire to wrap the rock, as opposed to sitting on top of it. The wrapping effect provides greater shear resistance, and in turn better traction. (Technically: the shear load is distributed over multiple planes, not just a horizontal one).

Tire spring rate: One of the great benefits of airing down a tire is improved smoothness. Less pressure allows the carcass to flex. A taller tire has greater sidewall compression, and in turn a better ride. (expressed as compressive strength=N/mm). That is why your grandma's Cadillac had such tall tires…

Negative Effects: Nothing in the world is perfect, so there are some downsides to using a narrow tire…

Stability and high speed deflection- A narrower tire (and in turn a narrower overall vehicle track width) provides less stability on the road and on cambered trails. In addition, a taller, narrow tire's sidewalls deflect more under severe turning forces, causing the inside of the tires contact patch (midline to the vehicle) to lift (roll in) from the road, increase the chance of a high shear force skid, or loss of control.

Increased potential for trail damage- A tall narrow tire has greater contact pressure, so when crossing a sensitive area like a muddy track, the tire will want to dig down until traction is found as opposed to floating on top. Make sure to air down and apply light, smooth throttle to minimize trail damage, or just turn around and save the trail from any damage at all.
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post #9 of 23 Old 05-11-2019, 10:45 AM
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Friend of mine had a 2015 JKUR with 35's on it. Got in an accident last year and JK was totaled. Bought a new JLUR and used the 35's off the JK on the JL rims and no problems wheeling all last summer. No changes needed to the JL

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post #10 of 23 Old 05-11-2019, 11:01 AM
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I ran 34x10.5 supper swampers on my TJ, the other tires I have run have been 33s and 35 12.50s.

I really can't compare them performance wise because the tires were all different BUT given the option I would choose thinner tires all day long just because they throw up so much less crap in and on the Jeep, so so so much less.

I have 15 inch rims so BFG ATs are the only option for thinner tires but they are overpriced and under perform. Dick Cepek used to have thinner tires for 15s. You have allot more options.

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post #11 of 23 Old 05-12-2019, 06:10 PM
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Quote:
Originally Posted by coloradoman View Post
I find a good rule is to use as tall a tire as possible with the same section width as the widest tire available from the factory for that particular model. That way the tire will compress into the wheelwell designed for that width, without rubbing due to width.

On an irregular surface like granite and boulders, a tires contact patch will deform as a result of vertical pressure. The wider the tire, the less the rubber will deform to the surface irregularity given the same vertical pressure. The greater the deformation, the greater the tires resistance to shearing forces (spinning).

When climbing a ledge with a jagged surface, the narrower tire will wrap the protrusions with more contact due to the increased deformation depth. The wider tire will rest on the surface of the protrusions and will have a greater chance of spinning (shearing).

As the vertical load increases, so does the compression and flexing of the tires tread and rubber to the surface protrusion. A narrower tire generates greater vertical load on the rubber and the tread, increasing tread compression in conformance to the surface irregularity. A wider tire in contact with more surface conforms less, and will shear sooner than a narrow tire.

On a highly irregular surface, the higher vertical load force of the narrow tire becomes an advantage, increasing molecular bonding between the tires rubber and trail surface.

It is not the contact patch that creates better traction, but the tires ability to conform to the surface irregularities (deformation and mechanical keying).
Great, great article about deformation, but I'll go ahead and point out a couple anomalies I see anyway.

First off, he suggests wider is better for soft sand, and then he quotes an overlander guy who says the exact opposite:

Quote:
Originally Posted by coloradoman View Post
A tall, narrow tire is a better choice for all off-highway surface conditions with the exception of soft sand, snow and soft mud that's depth exceeds 110% of the vehicles minimum ground clearance.

As quoted from Sahara Overland, a Route and Planning Guide by Chris Scott (2004):
"...Note that it's the diameter or height of the tyres that makes the difference in sand, and not, as many imagine the width... For the desert, you want tyres with a high aspect ratio of around 80 because this represents a taller sidewall so corresponds to added ground clearance when firm, and a longer contact area when deflated"

20% of the increased contact comes from the width. 80% of the increased contact patch comes from the tread patch becoming longer. A tall, narrow tire allows for a very long contact patch when aired down. That, coupled with the minimal frontal resistance (area), negates much of the downside to narrow tires in flotation situations. The taller tire allows for a long contact patch and still maintains good ground clearance.

It is not the contact patch that creates better traction, but the tires ability to conform to the surface irregularities (deformation and mechanical keying).

A tall narrow tire has greater contact pressure, so when crossing a sensitive area like a muddy track, the tire will want to dig down until traction is found as opposed to floating on top. Make sure to air down and apply light, smooth throttle.
Flotation seems like a poorly chosen metaphor. The vehicle is heavy, so it can't float. The assumption seems to be that soft patches of mud are narrow enough to allow wide tires to straddle terra firma. Maybe, maybe not.

The light throttle recommendation sounds more closely matched to sand driving. Momentum is definitely a big help in mud (not sand), and I've gotten myself through mud by stepping on it.

Quote:
Originally Posted by coloradoman View Post
Why do race cars use wide tires? Lateral stability and cooling. Performance cars have wide tires for handling performance not acceleration. A wider tire exhibits less "roll-in" or deflection which affects tire camber and handling. Performance vehicles also drive at high speeds, which generate heat. A wider tire has a greater surface area to dissipate heat (generated from cornering and acceleration forces) at speed.

A narrower tire (and in turn a narrower overall vehicle track width) provides less stability on the road. A taller, narrow tire's sidewalls deflect more under severe turning forces, causing the inside of the tires contact patch (midline to the vehicle) to lift (roll in) from the road, increase the chance of a high shear force skid, or loss of control.
The race car comparison is not ideal because they have lower centers of gravity and are unlikely to flip over without some help. Since the narrower tire can skid more easily, that seems like the safer choice for a truck. The skinny tire will skid before it tips over. The wider tire may tip over because it's less likely to skid.

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2011 KK Liberty (H&R lift springs, OldManEmu shocks/struts, skinny 32)
2009 Kia Sorento (H&R springs, ToyTec strut spacers, OldManEmu shocks/struts, skinny 31)
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post #12 of 23 Old 05-12-2019, 06:52 PM
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Quote:
Flotation seems like a poorly chosen metaphor. The vehicle is heavy, so it can't float.
He's not making things up or using words incorrectly (Dictionary definition number 4).
https://www.merriam-webster.com/dictionary/floatation

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post #13 of 23 Old 05-13-2019, 06:29 PM
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Thanks for chiming in! Don't get me wrong, I didn't mean to criticize. I just figured the author of the article is not around, so I could get incisive here without offending anyone.

Just sayin' that Merriam-Webster is full of metaphors, and their "dictionary" is not the word of god. No offense, but they're just a bunch of guys who are not very demanding, and don't really care about the language, they're just trying to generate internet traffic. Saying that I have to agree with Merriam-Webster's fourth metaphor is like saying I have to agree with CNN. Are they the Fourth Estate or the Fifth Column?

Hey Merriam-Webster, riddle me this: how much did you have to pay Rube Goldberg to settle his defamation lawsuit against you all?

No offense, but the pitfall in over-reliance on weak metaphors can be sloppy thinking. Many over-estimate the "advantages" of wide tires because they imagine they're floating. I have nothing against common usage of short words that everyone understands, and I would have done the same, but that excellent article provided by the OP makes a lot of strong arguments in favor of skinny.

2017 JK Sahara (my Smartcar)
2011 KK Liberty (H&R lift springs, OldManEmu shocks/struts, skinny 32)
2009 Kia Sorento (H&R springs, ToyTec strut spacers, OldManEmu shocks/struts, skinny 31)
2006 TJ budget LCG prerunner (see profile)
2006 Chevy Trailblazer (EXT lift, Nth LJ 4.5" springs + Monroe rear coilovers, skinny 32)
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post #14 of 23 Old 05-13-2019, 07:28 PM Thread Starter
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Ok so it seems really skinny tires are better for the wrangler. Why don't they have more skinny A/T tires? Matter of fact I can't find 1 A/T tire that has a high aspect ratio. Only M/T or these new R/T have the bigger sidewalls without the extra width. Why is this? anyone have any ideas? I would love to see an A/T tire in the 10.5 x 35s. I bet its because the wider tires just look better, they look more rugged and beefy for the mall crawler look.

So many advantages of skinny tires:
Less modding for larger sizes
Better MPG, less rolling resistance, air resistance, lighter
Better off road capability in almost every situation
Less wear and tear from lighter tires (brakes, transmission, etc)
Less time to air down and air back up
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post #15 of 23 Old 05-14-2019, 06:20 PM
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Quote:
Originally Posted by coloradoman View Post
Why don't they have more skinny A/T tires? I bet its because the wider tires just look better
Agreed, I would guess many are buying for the look. Some are just assuming wider is better, without reading much about it. Some have noticed that wider feels better.

Tire lift is great to have in the mudholes, and bonus if it was easily installed via skinny tires.

2017 JK Sahara (my Smartcar)
2011 KK Liberty (H&R lift springs, OldManEmu shocks/struts, skinny 32)
2009 Kia Sorento (H&R springs, ToyTec strut spacers, OldManEmu shocks/struts, skinny 31)
2006 TJ budget LCG prerunner (see profile)
2006 Chevy Trailblazer (EXT lift, Nth LJ 4.5" springs + Monroe rear coilovers, skinny 32)
1998 Dodge Durango (SuspMax & Roadmaster lifts, rear Truetrac, skinny 32)
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