Tire size opinion (1 Viewer)

Joined
Aug 15, 2016
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Plant City, FL
2000 LC 4 speed. Running 285/65r18 KO2s, which measure at 32.5 inch diameter. Looking to go to a true 34, Geolandar 003 MTs in 285/70r18, which measure out to 33.9. Truck is a pretty standard trail build, SPC uppers, 2.5" lift, but want some more grip.

We occasionally tow a 5200lb trailer, but no hills or mountains where we are at, no plans on towing to mountains. Running stock 4:30 gears and don't want to regear or change trans case OD gear.

So anyone have any thoughts or recommendations as to downsides of 34" tire size for how my truck is set up and what I use it for? I don't want to mess up shift points, and the downsides of 35s are too great to be a consideration for me.

Thanks!
Mark
 

flintknapper

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Unless you just want the 'looks' I don't see any distinctive advantages.

You're already lifted 2.5". The 70 series tire is about 1.5" taller in 'diameter' but the distance from the center of the hub/axle will be half that (the radius) so if you were looking for additional lift/clearance.....it will only be about 3/4".

The width of the tread will likely be slightly less than the 65 series. The 'footprint/contact patch' will be greater but marginal. I don't know how common a tire size that is IF you were to have to replace one. You'd want to have a like sized spare tire as well (and consider where you will store it).

You might compare the weight of each tire against one another too. As you've alluded to, the overall gear ratio will be affected by the additional height....but that's not the only consideration. A larger, heavier tire (if indeed heavier) is more unsprung weight, will affect braking and overall is harder on the steering.

For mild off-roading....IMO, you are already where you need to be. Often times 'tire pressure' (airing down) can be the answer to better traction or lockers.
 

JunkCrzr89

Competent Ignoramoose
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Jul 21, 2019
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Colorado
Unless you just want the 'looks' I don't see any distinctive advantages.

You're already lifted 2.5". The 70 series tire is about 1.5" taller in 'diameter' but the distance from the center of the hub/axle will be half that (the radius) so if you were looking for additional lift/clearance.....it will only be about 3/4".

The width of the tread will likely be slightly less than the 65 series. The 'footprint/contact patch' will be greater but marginal. I don't know how common a tire size that is IF you were to have to replace one. You'd want to have a like sized spare tire as well (and consider where you will store it).

You might compare the weight of each tire against one another too. As you've alluded to, the overall gear ratio will be affected by the additional height....but that's not the only consideration. A larger, heavier tire (if indeed heavier) is more unsprung weight, will affect braking and overall is harder on the steering.

For mild off-roading....IMO, you are already where you need to be. Often times 'tire pressure' (airing down) can be the answer to better traction or lockers.
x2
 

GTV

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Jan 31, 2019
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Si'ahl
It's hard to justify the price of the 285/70's when 275/70's are relatively plentiful and considerably less expensive. IMO the best way to get 34" is with a 17" wheel and 285/75's.
 

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