wheel size for 39.5's

[BionicCruiser]

i've been searching all day here and on pirate and it seems 6 of 1 half dozen of the other, but all posts were at least 2 years old. for you guys w/ experience running bigger tires-

i have tsl radials now in 36x14.5-15. i'm tired of ripping sidewalls. new tires this week will be Irok bias- 39.5x13.5. question is should i get bigger wheels with them? price is nearly the same for 15-17"wheel sizes. i wheel rocks in summer and snow in winter; almost no on road use.
i have the 15x10 steelies now. concerns are- balloon effect (of bouncing more on rocks), but better in snow; sidewall movement off camber and steering.

going to 16, 16.5 or 17s concerns- stiffer sidewall (6 ply vs. 4) needing lower pressures on rocks; cost of new wheels.

is there still the concern of no safety bead in 16.5?
i can do weld on beadlocks later on these 15's with the savings. after gears of course.

thanks for any advice. i've never run tires this big, and nobody in my club has anything bigger than 35's.

 

[brokenparts]

I ran 39.5s on 15s with no problem.

 

[mookie]

i have 39.5 iroks on 15x8 allied beadlocks, they work fine, no issues....BUT i will say that they are a little balloonish looking. the 39.5 iroks on 17" wheels look way better, more of a square tread profile. i've ridden with a guy running the 17's and haven't noticed any difference in traction....i wouldn't use 16.5's unless you're running hummer wheels.....

 

[cody c]

i went with 16x10's because i can get a heavier load rating with this size, i have a F250 and a fj80 that i can swap rubber between them if i need too, and its hard to find a decent 17" wheel 10" or 12" wide that isnt really expensive.
Although i do like the look of the moto metal 909's : MOTO METAL 909 Wheels from National Tire & Wheel @ NTW

heres a pic of some kiwis by my cruiser for reference...

 

[freds40]

15s tend to balloon. 17s tend to be more squared off (42s more so than the 39.5s) With a 17 you get less sidewall flex which is good in off camber situations.

I needed tires and wheels for my build and I preferred the look of the 17s. That said, I went with 17s mainly because the tires I found were for a 17. I'm interested to see how they work out this winter. They worked great in the sand

 

[R.K.]

The 39.5/15 Iroks are very "balloony" but the 39.5/17s are more "squared off". I have run both tires, and they both get great traction. I did get more wheel hop from the 15s due to the "balloon" effect.

Here is a pic of the 39.5/15s on 15x10" beadlocks on the left and the 39.5/17s on 17x9" beadlocks on the right.

 

['69 Yota]

The 39.5/15 Iroks are very "balloony" but the 39.5/17s are more "squared off". I have run both tires, and they both get great traction. I did get more wheel hop from the 15s due to the "balloon" effect.

Here is a pic of the 39.5/15s on 15x10" beadlocks on the left and the 39.5/17s on 17x9" beadlocks on the right.

Wow! That's a great picture showing how much difference the difference in rim size makes.

 

[BionicCruiser]

that IS a great pic for showing the difference! the difference in rounded tread is pretty big too. i do like the 17" squared look a little better. looks like a lot of sidewall sticking out there in the 15's. i'm good at catching those and ripping the hell out of them. anybody with either size on a 4000lb rig? i wonder how low of pressure i'll have to run with the higher load rating?
it looks like most people are running what rims they had or what tires they could get.

thanks for some great real world advice guys! i did put in an order for the 15er's, but i think i may call back tomorrow and move up to the 17's. cheap steel wheels are going for about $110. i may be able to pull that off.

 

[bustanutley]

I run the 17s, I think they are a great rim size for that size tire. Some people speculate that the little bit smaller sidewall keep the tire from hoping at lower pressures. I havn't lost a bead yet with these tires on a 17X9 rim; I rock 6psi. On my 37s I lost at least one bead every trip. Others in my group run 40s on a 15x8" rim and have never lost a bead, definitely the cheepest setup with no real need for bead locks. I would suggest beadlocks for the 17s as I have burped them here and there.

 

[woody]

17x9 is a very common rim size, and perfect for 37+ tires...I've run 39.5's and my current 37's on the 17" rims and have no complaints.

Also think resale...more likely to find buyers for the 17" rims....I wouldn't even consider a 15" rim anymore, and would be hard pressed to consider a 16", at least on the FJ40

 

[mookie]

also if you ever want to get a set of sticky tires they only come in one wheel size.....17"

 

[BionicCruiser]

i'm definitely looking long term. i don't want to have to get a new set of tires for several years minimum. my 36" TSL radials have lasted over 6 years (besides the sidewall ripped replacements). so i'm shooting for more than that for this set.

 

[DHONDAGOD]

I run 39.5 bias Iroks on an 8" x 15" wheel. Full figured cruiser and full hard doors and top in the winter. Snow pressures for me start at 6psi and I drop to 3 psi if I have problems. No beadlocks and have never lost a bead.

Granite pressure without the doors and top start at 8psi. Flex great and no issues with the sidewalls.

If I was starting from scratch Id go to 17's and not have 15's. I got 17's for the wifes rig and like the looks of them much better. Also the future looks like the mfgrs are going to the bigger rims anyways.

Chris

 

[BionicCruiser]

thanks Chris. my new 39.5's and 17" rims arrived and got put together today. i'll be picking them up tomorrow morning!
i'll put some pics up when i get them mounted.

 

[BionicCruiser]

i got them! i'll try to link pics here, but i'm having trouble. they are in a thread on my club's mud forum.

 

[BionicCruiser]

ahhh, it's working. the old ones are 36x14.5-15. here's more. 1st with my 8 year old son. yes almost as happy about the new tires as i am.

here's a new one on the right and an old one on the left.

and last one on the rig.

 

[lenross1]

congrats! what is the back spacing and width of your new and old rims?

 

[BionicCruiser]

what is the back spacing and width of your new and old rims?

old- 15x10, 4" BS
i ordered 17x8's and was told they were 5" BS. i didn't measure them myself. now i'm curious. i'll have to get to a tape measure and check them.

 

[BionicCruiser]

measured today. 17x10, 5" BS are the new ones. eventually, i want to put weld on bead lock's on them. that will be a little wider than i planned, but no problem.