Taller tires effects on handling

roaniecowpony

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I was thinking about some pizza cutters, M/T Boss AT 255/85R17 (35 x 10.0) tires. I'm just wondering about on-road handling. Is steering sloppier? More sway?

Also, wondering if a lift is needed for this skinny a tire. What do you think it will do to the mileage?
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Fsttanks

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Handling as far as tire grip will be different compared to your current tires because of the MT tread design. They will not handle as well as street bias or AT tire.

If you have a Rubicon then they will fit with no issues.
 

Yellow Cake Kid

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Taller tire effects on handling?
Up sizing the diameter of the tires will increase front wheel trail, which can marginally increase the sensation of stability.

Up sizing the diameter of the tires without changing wheel offset will decrease the scrub radius, which can marginally decrease the sensation of stability.

The two factors will affect the handling sensations in different ways, and will not specifically negate each other, so the result is that the front end will feel marginally different, but unlikely to feel "bad".


One nice thing about large volume tires is that they can absorb heat with less air pressure than a lower volume tire can. You have to pressurize the lower volume tires with more air molecules to equal the heat sink capability. If you select a larger diameter tire with a slim width, you will want to run them at higher pressures than a similar diameter tire with greater girth. Will that decrease rolling resistance and improve mileage? Maybe, but you might want to consider the opportunity cost; enhanced comfort can be safely realized by running higher volume tires at relatively lower pressures, and you will forsake that if you opt for a skinny tire.

You might want to spend a few minutes working your way through one of the tire size air pressure comparison calculators to get a feel for this.

Good luck.
 
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roaniecowpony

roaniecowpony

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Just to level set, I have a JLUR, currently on stock 285/70R17 KO2. And my candidate tire is a Mickey Thompson (M/T) Boss AT (All Terrain). So, the change would be about 1.8" increased diameter, and about 1.1" narrower.

Probably my biggest concern is the taller sidewall stability and steering response. I recall having some tires on a truck that had terrible steering response and the sidewall stability let the truck feel like it was wallowing around. I had to change them out before they killed me.
 

David P.

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I installed 37” Baja Boss ATs on my 2021 JLUR with a 2.5” lift.

I did spend the extra $ to seriously beef up and replace all of my steering at the same time…instead of waiting for my stock steering to wear out in 10k miles.

Probably could have waited, but I just went ahead and did it all at once.
 
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roaniecowpony

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I installed 37” Baja Boss ATs on my 2021 JLUR with a 2.5” lift.

I did spend the extra $ to seriously beef up and replace all of my steering at the same time…instead of waiting for my stock steering to wear out in 10k miles.

Probably could have waited, but I just went ahead and did it all at once.
That was a good idea, especially with 37s. One member on 37s here posted a picture a couple years ago with his OEM tierod buckled right where they put a hole and a rivet.

I also beefed up my steering, but for other reasons (wandering). I have Steersmarts; trackbar, draglink, and tierod. I'm planning on installing cast iron Reid knuckles and Dynatrac balljoints. My dealer has ordered the cast iron steering box. So, I'm in pretty good shape there.
 

David P.

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That was a good idea, especially with 37s. One member on 37s here posted a picture a couple years ago with his OEM tierod buckled right where they put a hole and a rivet.

I also beefed up my steering, but for other reasons (wandering). I have Steersmarts; trackbar, draglink, and tierod. I'm planning on installing cast iron Reid knuckles and Dynatrac balljoints. My dealer has ordered the cast iron steering box. So, I'm in pretty good shape there.
Yeah my Jeep came with the steel steering box and has been fine while stock. Drive very smooth for a Jeep with 33” tires.

then again, my last Jeep point of reference was my old ‘84 CJ-7 with a lift and mud terrains from 18+ years ago, so the JLUR feels like a Bentley compared to that.

I went with RPM 2.5 ton steering, S Smarts Poly Pro track bar and a fox stabilizer with S Smarts relocation bracket. Super beefy and more than I’ll ever need.

When my ball joints wear out, I plan to go Reid knuckles and dynatrac ball joints, just like you.
 

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Up sizing the diameter of the tires will increase front wheel trail, which can marginally increase the sensation of stability.

Up sizing the diameter of the tires without changing wheel offset will decrease the scrub radius, which can marginally decrease the sensation of stability.

The two factors will affect the handling sensations in different ways, and will not specifically negate each other, so the result is that the front end will feel marginally different, but unlikely to feel "bad".


One nice thing about large volume tires is that they can absorb heat with less air pressure than a lower volume tire can. You have to pressurize the lower volume tires with more air molecules to equal the heat sink capability. If you select a larger diameter tire with a slim width, you will want to run them at higher pressures than a similar diameter tire with greater girth. Will that decrease rolling resistance and improve mileage? Maybe, but you might want to consider the opportunity cost; enhanced comfort can be safely realized by running higher volume tires at relatively lower pressures, and you will forsake that if you opt for a skinny tire.

You might want to spend a few minutes working your way through one of the tire size air pressure comparison calculators to get a feel for this.

Good luck.
Not your first rodeo … good read.
 
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roaniecowpony

roaniecowpony

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... but you might want to consider the opportunity cost; enhanced comfort can be safely realized by running higher volume tires at relatively lower pressures, and you will forsake that if you opt for a skinny tire.
...
Good luck.
That's a rabbit hole I don't want to go down. Larger dia and wider will drive a change to a lift and wheels. I don't want to lift it.

But I mess around on the calculators. I couldn't find one that had that size (255/85R17) but bracketed it. Looks like somewhere between 0 - 3 psi increase for the pizza cutter. I still have time. Maybe Mickey Thompson will have more selections by the time I need tires.
 

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When I went from the stock sport street "AT" tires to rubicon falken M/Ts I didnt feel different in handling. In fact the falkens feel better. Mind games. Id say go and get your bigger tires.
 

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My 35x11.5x17’s Toyo AT3’s may not fit your “pizza cutter” look, but are an excellent tire. Load range C and light weight. They are on our 2020 JLUR with a 2” lift on the stock rims. I am extremely happy with them and they handle very well.
 

Yellow Cake Kid

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With regards to the pressure, comparison of recommendations that are like to like e.g. LT-metric or Flotation (USA tuck tires) will reveal the air pressure differences more readily than comparing tires that may have significantly different structural components.

Comparing a LT-metric to a Flotation type construction in these sizes is likely as the sizes overlap in measured dimensions, so you may not see as much deviation in recommended air pressure because the structure of the tire differs enough to compensate.

In other words, if you compared LT-metric to LT-metric tires (not just translated labeling) you will see greater differences in recommended air pressure as the volume changes, and if you compare Flotation to Flotation tires you will not see much difference in recommended air pressure, because the tables are arbitrarily constrained by a minimum recommended air pressure, such as 35psi, but you may realize that the same minimum air pressure will result in marked differences in weight bearing capacity as the volume of the tire changes.

On the other hand, with all the glossy photograph marketing that occurs in the light truck and SUV industry, it is not readily apparent which LT-metric or Flotation tire in the applicable sizes are truly manufactured with differing structure, so the guidelines may or may not apply as accurately as would seem beneficial to end users.

Having said that, it's all sort of academic, as you will likely have higher priorities regarding your choice of tire.

Good luck!
 
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I ran 33x10.5x15 on an Xterra with no sway bars. I had no issues with stability in town or highway.

I was happy to have the pizza cutters because a 12.50 would have required significant fender modification with a saw-z-all.
 
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