Inherited CJ7

[Lumpy Grits]

If you run BFG/AT in 33", you'll be very pleased. Very quiet on road, fantastic off/on road traction and great tread life.
I really don't understand the 'hard to manage' deal at all.
That hardtop and doors were factory OEM. Don't worry about any weight concerns.
LG

 

[Hedgehog]

Lumpy - I was being non specific because some CJ's have move difficulty than others with tires bigger than 31's. Gearing can be an issue, ride height, suspension adjustments for the height and weight of bigger tires, along with the handling issues that pop up and turning radius issues. With the added weight of the tires suspension can be compromised, braking issues can be a problem along with the added weight strain on spare tire carriers.

Some issues are minor, some can be major. Big tires are cool looking and can offer a degree of ground clearance, but it all comes with a bit of a premium.

 

[Lumpy Grits]

Good point HH-
The CJ must be set up for the tires you choose.
You only have to do this once tho-
The 33'' tires combined my 5 speed, is the reason I went with 4:88 R&P.
IMO, the biggest issue with large tires on a CJ are the go-kart sized brakes used on that mod 20 rear.
LG

 

[HackFabrication]

Big tires are cool looking and can offer a degree of ground clearance, but it all comes with a bit of a premium.

One of the first decisions anyone should make when modifying their vehicle, whether Jeep CJ or other, should be tire size. So much depends on what size rubber you want to stuff under the vehicle.

IMO, the biggest issue with large tires on a CJ are the go-kart sized brakes used on that mod 20 rear.

Maybe on the later CJ's. Mine has 11" x 2" drums in the rear. Couple that with a disks on the front and a hydroboost braking system, and it stops my 32x11.50-15 tires: Right Now. Maybe one day, when/if I do blow up the AMC20 and upgrade to a Dana 60 or Ford 9", I'll add disk brakes to the rear.

 

[HackFabrication]

Oddly enough 32's used to be popular, that size seems like a great compromise, but are difficult if not impossible to find today.

Problem seems to be more in finding them in a 15" wheel size. IIRC, my son's JK came with the metric equivalent of 32's.

 

[Lumpy Grits]

Hack-I'm run'n shoes on my Currie 9" and have no issue locking the rear tires(33")anytime I want. I can also back down a hill and have full braking control without the fronts locking up. When I had the 20 in-I couldn't do either.
The other advantage to the shoe deal, I'm still running the OEM type master cyl and the p'brake hook up for the 9" was simple.
I do believe AMC did downsize the rear brakes on the 20. Just don't know when.
LG

 

[HackFabrication]

I do believe AMC did downsize the rear brakes on the 20. Just don't know when.

It was either with the 79 model year or in 79 for the 80 models. Information seems to be a bit sketchy, but as we all know, AMC liked to use up old parts before switching over. Those later CJ's, got 10x1.75" rear drums on the AMC20 . Not sure what size drum was on the Dana 44 's that got put in after AMC ran out of the 20's with the last of the 86 models.

On a side note, my 76 CJ5 came stock with 4-11x2" drums and non-power brakes. Disk front brakes and power brakes were both options. I left the OEM 11x2" rear drums (total rebuild), because I knew they wouldn't have any problems with the tires I planned on running. However, I converted my front drums, to disks using parts from an 84 CJ7 . I gave up the 6 bolt hubs, but added MileMarker locking hubs in place of the poor Warn hubs. Haven't challenged anything yet with the front locked, so I'll reserve judgement until then...

Somewhat on topic for the OP: Had I known then, what I know now, I would have bit the bullet and opted for the custom Dana 44 front and Dana 60 rear. Or went with custom Ford 9" front/rear.

 

[Hedgehog]

Problem seems to be more in finding them in a 15" wheel size. IIRC, my son's JK came with the metric equivalent of 32's.

Well yes, I was talking about standard CJ rims. Never really give anything newer than '86 much consideration.

 

[HackFabrication]

Well yes, I was talking about standard CJ rims. Never really give anything newer than '86 much consideration.

Trust me, I like the 5 on 5.5, 15" wheels too, but if I could find a 17" rim with a 5 on 5.5 pattern that I liked, I'd consider it.

Of the one's I've found, these are almost there: https://www.summitracing.com/parts/vsw-84h7885ns/overview/

 

[Photonfanatic]

33's are getting a little on the hard to manage side. There seems to be a break point between 31's and 33's. Without doing any modifications to the suspension 31's are very popular and for many really get the job done. 33's are only a little bigger but the increase in weight is something to consider in your choice. 35's are much heavier and require a lot of suspension work to work well on a CJ. I have always run 31x10.5's on my CJ's, but like you I'm hearing the call of 33's. Oddly enough 32's used to be popular, that size seems like a great compromise, but are difficult if not impossible to find today.

Can I get a few of you guys who are currently running the 31" tires, to post up a few pics of your jeeps? I'd like to see what the 31" tires look like.

 

[Hedgehog]

This is an early picture of my '75 CJ5 :

 

[Posi]

31's look good on your rig.

 

[HackFabrication]

Can I get a few of you guys who are currently running the 31" tires, to post up a few pics of your jeeps? I'd like to see what the 31" tires look like.

Not 31's, but my 32x11.50-15 TSL/SX are close to 31" mounted on 8" rims. 2.5" BDS lift, near stock ConFerr shackles:



Like I posted earlier, if you've got to go out and buy tires, think about swapping in 17" wheels. Lots and lots of choices in the metric sizes. Also Super Swamper has a good looking 34x10.50-17 LTB, if you want to go with an aggressive tread, a 3" lift, and a 1" body lift. Should have Limited issues running mostly mild trails with that size and setup.

All terrain, it's hard to beat the offerings from BFG. Great wear, good compromise tire.

 

[Lumpy Grits]

The big downside of run'n the 17" rims. Is the reduced sidewall flex/traction off road, when compared to a 15" rim and same tire diameter.
Me, I'll stick with 15" rims.
Respectfully,
LG

 

[007]

Here's mine with 31's and no lift besides 1" shackle in front only.

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[007]

The big downside of run'n the 17" rims. Is the reduced sidewall flex/traction off road, when compared to a 15" rim and same tire diameter.

Me, I'll stick with 15" rims.

Respectfully,

LG

I agree completely. I'm starting to see JK's with 15's for this very reason.


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[HackFabrication]

The big downside of run'n the 17" rims. Is the reduced sidewall flex/traction off road, when compared to a 15" rim and same tire diameter.

I do agree with that. Like I posted, I like my 15" rims for a lot of reasons. However, on a mostly street driven Jeep, that will only see mild trail use, I think it's a viable option that should be considered.

 

[Neuner]

I agree completely. I'm starting to see JK's with 15's for this very reason.


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That would be a good sign/cause for them to rethink production of the 15" sizes if they become popular again. Problem is that I think most of those guys run 35" or 37" don't they?

 

[007]

That would be a good sign/cause for them to rethink production of the 15" sizes if they become popular again. Problem is that I think most of those guys run 35" or 37" don't they?

When we were all out in Colorado last summer I saw several JK's with 15" steel rims and 33 inch tires on them. But yes, to your point, there are a lot of folks running those big tires on 15 inch rims on a JK as well.

 

[Posi]

I'm running 17 tires for offroad use with with plenty of traction, I'm also running 16.5" wide.

15 is a better tire for offroad use, they will give you a softer ride, and good traction when aired down. The downside compared to 17 is the tire can roll easier when aired down. You will find more damage to a 17 rim compared to a 15 rim when using offroad.

For the road and light trail use 17 is a great choice with more tire options then 15.