Help picking tire size - pros, cons

[djsherif]

Hi guys,

I currently run 33x12.5x15 A/Ts on 15x10 Mickey Thompsons for summer but don't like them so I've settled on the BFG KM2s in 35" after hearing such great reviews and trying them on a friends truck. They also look bad a$$. I'm curious as to the pros and cons of the following sizes:

35x12.5x15
35x12.5x16
35x12.5x17
315/75/16 = 34.6"
305/75/17 = 35"

The variables here are the wheel diameter and the method of calculating size. That being said, here are my questions:

Why go with a 315/75 vs a 35" for example? pros, cons if any

Why go 15" vs 16" vs 17" for the wheel? pros, cons if any? How do the different wheel size affect handling on and off road?

Thanks to all in advance.

 

[blzrfn]

The main differences are cost and weight rating. 15" tires tend to be the least expensive but have the lowest weight rating.

 

[djsherif]

You are correct, the 35" tires in 15s are rated at ~2500lbs and the 16s at ~3200lbs but for my purposes I don't think that makes a difference to me. Would the shorter sidewalls on the 16s and 17s mean better on road handling with less bounce/wobble?

 

[iptman]

No love?!

What no love for the 255/85 16?! $75 less per tire than 315's and only less than an inch shorter (~34").

 

[ForealBoreal]

with 16s your going to save money comparing to 17s.
15s are a pain in the ass, your really limited by sizes.
get some 16s and go 255s or 315.
i have concidered the 17s and going to 285/17/17 (34 inches tall with 11.5 wide)
you also have a pretty monster lift on that truck too....

 

[djsherif]

I guess I will sell my 15s then and buy some 16s.

For the 255/85/16 those are actually 33.06 so ~33" which is what I have now. 255/85/17 would be ~34" and definitely an option but I really like the extra height.

I have 245/75/16 on right now for winter and they look tiny

 

[d0ubledown]

16's are kind of the bastard size for 35' theres limited selection for a true 35. 15's & 17s have more selection for that size. sure you can get 315's but put a 315/75/16 beside a 35X12.5X15 and the 315 will not only look narrower, but shorter. because in reality...they are. forget what the metric equivalent tells you. 315's arent a true 35X12.5

since you can run 15's id go with a 15 unless you plan on a big brake upgrade. i doubt you'll exceed the load ratings on the 15's. D VS E ratings will affect your ride handling more than the height of sidewall. interco actually offers a 34" in their popular trxus model.

 

[jlg32281]

What usage does your truck see? DD or trail rig?

 

[djsherif]

d0ubledown, thanks for the feedback. Are you saying that the 315/75s are not manufactured with the same precision as the 35"? Calculating the size gives negligible difference in height and width, how could they look so much smaller as you say?

jlg32281, my rig is currently a DD with 10% trails (no rock climbing) but with the 35's I hope to drastically increase trail time.

 

[d0ubledown]

d0ubledown, thanks for the feedback. Are you saying that the 315/75s are not manufactured with the same precision as the 35"? Calculating the size gives negligible difference in height and width, how could they look so much smaller as you say?

have a look at my findings here:

IH8MUD.com - View Single Post - 37's

not so much presision..just different measuring sticks and the way the industry and the wheelers @ large interpret what the manufacturers are telling us we are buying...

 

[djsherif]

interesting how the sizes vary...ah, the wonderful world of marketing...will 17's handle better on road than 15s with the shorter and presumably stiffer sidewalls?

 

[Ihasfip]

I will post this again. 315/25.4=12.4" wide. 315mm x 75% = 236.25mm 236.25mm x 2 = 472.5 472.5/25.4 = 18.60" + 16 " = 34.6" OD.

285/25.4= 11.22" wide. 285mm x 75% = 213.75mm 213.75mm x 2 = 427.5 427.5/25.4 = 16.83" + 16" = 32.83" OD.

Granted there are differences between manufacturers but that is a close estimate to all 315s.

You can plug any size tire in to that formula and figure out the size.

HTH.

D

 

[djsherif]

ya, I know about the calculations and the variations but I'm more interested in the different handling characteristics of the different sizes.

Can anyone give feedback on that?