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View Full Version : 40s vs 37s



nacho
01-31-2012, 01:43 PM
as the title states, I am on 35 mtrs right now, I have not been impressed much by these tires in the places I wheel. Granted I am coming form trailered rigs running bias IROKS, so I am most likely just having a hard time with the compromises. Anyway, Ordered some new wheels and can switch to either size, just wondering what is the real world difference on a JKU between the sizes. Besides the obvious size difference and additional 1.5 or so axle clearance. I decided to go with a 17inch spyderlock. Had a hell of a time debating between 20 and 17, spyderlock discontinued the 20 so my mind kind of was made for me.

wayoflife
01-31-2012, 02:51 PM
i've run a lot of tires and honestly, MTR's have been my least favorite so far. they were hard to balance, rode wired on pavement, were unpredictable on the trail and, had weak sidewalls. i suspect that if you had run a different tire, you might have been happier. having said that, 37's are a great size for a JK and one that's just at the threshold of what a set of factory dana 44's can handle. if you really wanted to go 40, i would strong recommend upgrading your axles to something like dynatrac prorock 60's.

piginajeep
01-31-2012, 04:02 PM
not to mention steering uppgrades and everything else that starts to go when 40's are under the JK.

wayoflife
01-31-2012, 04:38 PM
not to mention steering uppgrades and everything else that starts to go when 40's are under the JK.

too true. it's bad enough trying to work 37's without a PSC ram assist. with 40's, it's near impossible.

Hightower
01-31-2012, 05:22 PM
I have 40's and PCS and D44 if i do one axle at a time which would you do first (front)?

nacho
02-01-2012, 01:04 AM
i've run a lot of tires and honestly, MTR's have been my least favorite so far. they were hard to balance, rode wired on pavement, were unpredictable on the trail and, had weak sidewalls. i suspect that if you had run a different tire, you might have been happier. having said that, 37's are a great size for a JK and one that's just at the threshold of what a set of factory dana 44's can handle. if you really wanted to go 40, i would strong recommend upgrading your axles to something like dynatrac prorock 60's.
unpredictable is the best way to describe them. Didnt have any balance issues, ride is ok if a little into following cracks and such. Abused the sidwall and never had an issue. It is the way they are a box of chocolates in the rocks, you never know what kind you are going to get. I think I am going to just go to a true 37 for awhile and just have 40 envy. As far as I know there are no options for hydro assist on a 2012 yet, have a lot of little sorting out to do on my setup before switching to d60s anyway. As bad as I want 40s I think I will be smart and just go to a really good 37, the nitto trail is 36.85 inches, the mud is at a true 37. I am about set on giving nittos a try this go around. I like that they are heavy as in offcamber stuff the unsprung weight can work out to your advantage. In my old trail rigs I ran either a 36 (actually a 37) or a 39.5 irok on 15inch wheels with about a gallon of water in each wheel. Granted these where trailer queens and almost never saw speeds over 30mph. In fact I am not sure my truggy could get over 45.

nacho
02-01-2012, 01:05 AM
I have 40's and PCS and D44 if i do one axle at a time which would you do first (front)?

which ever one breaks first :idontknow:

wayoflife
02-01-2012, 01:24 AM
I have 40's and PCS and D44 if i do one axle at a time which would you do first (front)?

it's way more expensive but, i would get the front first. the factory d44 won't hold up for long on the rocks but, you can kind of make the rear work out for a while.

Hightower
02-01-2012, 06:39 AM
it's way more expensive but, i would get the front first. the factory d44 won't hold up for long on the rocks but, you can kind of make the rear work out for a while.

I thought you ran your d44 rear for a while? Im going to have to price it out talking with Greg and now you I'm probably best to try and swing both axles at the same time. Thanks for the advice.
Chris

wayoflife
02-01-2012, 06:45 AM
I thought you ran your d44 rear for a while? Im going to have to price it out talking with Greg and now you I'm probably best to try and swing both axles at the same time. Thanks for the advice.
Chris

i did. prorock 60 up front and dana 44 rear. lasted about 2 months and 10 difficult trails before the 5.38 pinion blew. if you stick with 5.13's, you can probably make it last longer but, running 40's, it might be kind of a dog.