What is considered "One Size Up" in Tires?

JMyerz

Adventurer
I've got a 2014 Ram V6 8Speed transmission and 3.21 gears, it was a great deal and I rather like the V6 so I plan on keeping it. Its been suggested that I don't go up more than 1 tire size from stock. I currently have 265/75 R17 (31.7") Tires and not sure what "one size" should be? Would a true 33" be too much or should I shoot for more like a 32.8".

I saw my truck on 34" and it looked perfect but I fear that might be to tall of a jump.

Thanks!

Justin
 

justcuz

Explorer
One size up would be 285/75x16. Usually about a 32.5 to 32.8 tire diameter.
It will be wider and taller than your 265/75x16 tire because the aspect ratio is the tire width of 265mm with a sidewall that is 75% of the tire width. As the tread widens the sidewall gets taller given the same aspect ratio.

Your gear reduction with that 8 speed is pretty low.
My 2015 Suburban has a 6 speed trans with 3.42 gears. 1st gear is 4-1 so my ratio is 13.68.
My 2000 Suburban has the 4 speed trans with 3.73 gears. 1st gear is 3-1, to achieve the same 13.68 gear reduction, I would have to have 4.56 gears in my 2000.
 

Martinjmpr

Wiffleball Batter
One size up would be 285/75x16. Usually about a 32.5 to 32.8 tire diameter.
It will be wider and taller than your 265/75x16 tire because the aspect ratio is the tire width of 265mm with a sidewall that is 75% of the tire width. As the tread widens the sidewall gets taller given the same aspect ratio.

Your gear reduction with that 8 speed is pretty low.
My 2015 Suburban has a 6 speed trans with 3.42 gears. 1st gear is 4-1 so my ratio is 13.68.
My 2000 Suburban has the 4 speed trans with 3.73 gears. 1st gear is 3-1, to achieve the same 13.68 gear reduction, I would have to have 4.56 gears in my 2000.
.
He has 17" wheels so I think the equivalent would be 285/70/17. ;)
 

Choff

Adventurer
Check online for conversion chart on tire size and how the speed is affected, I went up one size and my upper end speed increased. I drive by the GPS now anyway.
Did not affect any thing else.
Choff
 

justcuz

Explorer
Sorry about the typo, yes his would be a 17" wheel. Was just comparing to my 16" and did not correct to his 17" wheels.
All other info is relevant though.
 

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