Birty Dastards Jeep Club
Tech Forum => Workshop => Topic started by: Dave69 on September 11, 2009, 01:54:06 PM
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if your fitting 33x12.5 tyres what rim would you use ? A 10" with or the smaller 8.5".
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wahey, i can answer :icon_super: (tho fully understand if u wait for a 2nd opinion)
my v first birty post was on this, and the replies were unamiously 10", in fact, major doubt was expressed on whether u would find a tyre fitters that would fit them officially on an 8"
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look at our yj ( avatar) thats got 33x12.5 and they look great, you don't want to touch 8'' rims with anything less than standard tyres other wise you will be blown all over the road due to the sidewall flexing
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you have approx +/- 25% on nominal width to rim but if you look up the spec sheet for the specific tyre it will give a recommended rim range, I have 31x10.50 on a 7 1/2" rim and is the lowest recommended rim width for my tyre.
it will vary from make to make due to side wall construction, the reason being the bead needs to rotate into line with the rims bead seat.
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I had 33" on the CJ,33" on the Toyota and 33" on the Shogun,all on 8jj rims and all with no problems at all
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I had 33" on the CJ,33" on the Toyota and 33" on the Shogun,all on 8jj rims and all with no problems at all
Even when offroading,and you all know what im like offroading......... :003: :003:
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i've been looking at bigger wheels for some time but always put it off. Cheapfest relit the frustration with ground clearence on the diffs. 33x12.5 is the max for the 8" rim but unsure on the sidewall shape/stretch. the 10" offer more choice of tyres. I'msticking at 33's so unsure whether to run the 8.5" or just pay that little more for a 10".
I may have answered my own question for tyre size, and the size choice for 10.5" wide tyres are limited to a small choice of makes where as the 12.5" choice is more abundant. Just wondering peoples opinion on running 12.5's on a narrow rim and a wide rim.
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tank just sold me on the ten inch rim way to go
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we had planned to go 33x12.5 on the red truck and i had 4x10" rims waiting but knew how the truck performed on 33x10.5 so we went that way on 8" rims
for me- 12.5 needs 10" and dont forget your backspacing so you have a good turning circle
aint you going to have to do some metal cutting to go 33
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My 33`s were all 12.50 on 8jj,its only my 35`s that are on 10jj but then they are 13.5`s
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yep fender cutting will happen plus some extended bumpstops. After a bit of tinternet browsing the 10" looks the way i'll be going plus they have the backspacing to push the wheels out. Might be ready for Turkey Hunt if wifey dont spend the money
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I have no idea what drivetrain you have Dave, but you need to be thinking about stronger
shafts if you're using a D35, and a re-gear. 31s are bad enough with stock 4.0 gears,
nevermind 33s. Oh and also be thinking about new fender flares - which will rub if you have
too much offset. Then you'll be needing a 5.5" lift too to get any decent artuculation, and
that much lift needs a SYE.
Of course I've not seen your XJ for prolly 18 months, so you might be all ready for 33s.
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I had 32x11.50`s on my old XJ and that had a RE 4.5 inch lift and to be honest that was about right for articulation etc,might have been pushing it a bit with 33`s
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the jeep is 3.5" at the moment, going to 4.5" at the front and 4.5/4.75 at the rear. the axles have been swapped for 4.11 ratio's and with the 8.25 rear axle. A little stronger than the dana 35. UJ's have been swapped for the stonger type and axle shafts might be swapped if funds allow. As for the SYE that will be addressed if i have imediate issues.
32"x11.5x15 i am considering as i will reduce the stresses on the axles plus i will not have to trim to excess, plus it reduces the cost slightly, fender flares are to be swapped for some TJ ones to give the coverage.
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I run 33s on similar axle setup (8.25 rear, D30 front. Uprated shafts, lockers etc.) and have no problem except would like deeper gearing. Saying that, I do like rocks more than mud and the rocky stuff really needs a crawler transfercase and even lower gears.
I do have 6" long-arm lift for my 33s but reckon I could fit 35s under that lift with the trimming and TJ flares I have. Going to the higher lift and bigger tyres I think you should consider brake and steering upgrades too.
Back to original question, 8" or 10" will work. 8" can be better holding a tyre when using low pressures offroad. I use 7" rims with 285 tyres (11.3") and can run at 13-14 psi no problem. Getting tyres fitted to rims outside the 'recommended' size range can be problematic so 10" might be a simpler route.
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I have a set of (5) 32 x 11.5 x 15 BFG MT's on 3.75 inch backspaced steel rims sitting in the garage (swapped to 33's) waiting for me to rub down and paint the rims before they go up for sale.
Spare is unused, the other 4 have battle scars and maybe half worn.
I don't have time to paint them for a few weeks so if it would help to try these during that time and you can collect from near Stratford then let me know.
Tony
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i run 33.12.50's on standard yj rims. never had any probs even runnin soft.
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:imwitstupid:
I've run 31s, 33s, 35s and now 36" Simexes, 10.50s, 11.50s and 12.50s on rims no wider than 8". Never had a problem.
And another Bucks Jeeper is running 38/12.50x15 Swampers on 8" rims in challenge events. Again, never had a problem. :icon_super: :icon_super: :icon_super:
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:imwitstupid: Yep. 8s are what I've run on the YJ since 2000 and had 33s and now 35s with no probs. Run 26psi on the street and down to 8psi on the rocks and never once blown a bead.
A mate has run the same tyres over the same time but on 10s and has blown a least 4 beads when with me and probably more at other times. Now he's running staun beadlocks on the front and has ripped the valves off cos they are rigid and not flexible rubber like normal.
So between us we're getting good with the hairspray and the lighter ..... icelandic bead re-seating trick!!!
Bottom line run 8s
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Yeah I run 285/75 R16 on stock rims 7J, down to 7psi no prob.... but when I go that low on Swampers 34x9.5 then they can pop off, so run them at 10/12.... also carry spare valves... handy....
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that's great more infomation to confuse the decision. might have swayed the idea to 8 but the back spacing might be an issue and spacers might be needed to kick out the offset. back to my spreadsheet for tyres and sizes
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Get a min 4" backspacing, the less the better -more clearance, more width...
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hence the initial view to go with a 10" rim as the back spacing is mostly 4" (std i think) where as the 8" will need some spacers to get to this offset
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ideal plan is to get some 15" rims of 8"+ size but i also have a set of 16" alloys so i might stick a set of 285's on them and see what happens. Backspacing will most likly be need for these as well ?
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I run 285s on 4" backspace 16x7s and it works well, no rubbing on my setup but it's all about fit, test, adjust when modifying at this level.
P.S.- I think that's a standard size too 'cos all the 16x8s have about 5" of backspace.
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Not speaking from any technical point of view, just experience.....
Running BFG MT 31's on standard Wrangler alloys, aired down to 12 psi & popped a tyre off a rim in deep ruts, may have a little too keen on the loud pedal to clear the obstacles but I ain't aired sown since :003:
PS, no hairspray needed, just re-inflated with our compressor & it popped back in place a treat, lucky I guess :icon_super:
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13 psi is my normal offroad pressure and I haven't blown a bead yet, could be luck though - certainly not skillful driving :icon_rolleyes: