Sooooo I have had my heart set on 37s on 18" procomp wheels. I just ordered my wheels, along with some other goodies (intake/exhaust/tuner,etc). Then I ordered my dual battery kit from benchmark, and saw their jeep on the site with 39.5" iroks. It looks so mean! I guess what I'm asking is that will I be happy with 37" nitto mud terrains or am I going to want to go bigger?

 

You can always go bigger, how deep is your wallet? Do you have the money to spend to upgrade all the things that would be needed to run a tire that big?

 

IMO, 37s are the sweet spot. 39s are cool but the mods for running them are spendy.

Bigger axles. I went Currie 60s with 5.38.
Hydro assist steering.
Serious suspension kit. I went with the Teraflex 6" Elite Long Arm.

Just those parts alone are around $16K.

39s-40s are spendy tires. Most people want to run a moderate radial like a Toyo, KM2 or MTR. Be prepared to spend as much as $500 a tire. I went with the IROK bias ply. Forget everything anyone has told you about bias swampers. Mine run smooth, don't flat spot, have tougher sidewalls, are way lighter than a radial and are around $315 a tire. Love them.

Another problem with 39-40s is gearing. Even 5.38s leave you wanting more gear. This is me speaking from experience running lightweight 39.5s. An ideal gear ratio would be 5.89s but you can't get those in HP60s. Currie has 609s that would allow you to run 5.89s.

37s will go 95% of the place 39s will go. I do like the big swampers in the deep snow that we get here in the Cascades, but after 37s, it definitely diminishing returns.

Just my $.02

 

Thanks for the info John and everyone else! I'll stick with the 37's and be happy with that Now to decide I should get the 3.5" Midarm kit or the 5.5" one.

 

Which manufacturer?

 

I run the 3.5 midarm with flat fenders and 37 Toyo. Its a great combo

 

Rock Krawler i believe

 

I do love my 37 Bias Iroks. They are as good or better on the road than the Mud Grapplers and kick a of road.

 

Dang Mike, bias Iroks that run better than your Grapplers? Huh. Would not have thought that!

 

Yup! I had a chance to meet Jeremy a couple weeks ago, and he knows a lot of the motorsports guys that I know in the Albany area. Can't pass up the sick deal

Awesome. That's what I wanted to hear! I'm thinking the 3.5 X-Factor Plus with bushwacker flat fenders!