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33x12.50x15 bfg km2 on stock 15x7 alloy wheels

89 jimmy

89 jimmy

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Hello everyone, new member to a great site thanks for all the info. my first question is I have an 89 gmc jimmy with 2.5 in lift and 32 in bfg at. can I run a 33x12.50x15 on the stock 15x7 alloy wheel? will it be safe for highway driving? Thinking of going with 4 in lift and 33,s is there any negatives as far as gearing (stock gears now) and tranny problems etc.? Thanks. Use mostly for onroad driving with a little offroad fun too.
 
I drive a '90 with the stock aluminum alloys (15x7) completely stock suspension and no fender trimming and I'm running 33" 12.50 R15s Kumho A/Ts

DSCF4255.jpg


I know they aren't BFG's but they should be close. I do notice the truck is a little slower with the stock 3:42 gears going from 31" tires to 33" tires. Also the cruise acts kinda funny on the highway when going up and down hills, could be a problem with my cruise control, but it doesn't happen when I run the 31" tires. The tires fit good, hold air good. But I noticed when I took them off the truck that the tread is wearing kinda funny. When looking down on the tire it appears to be slightly M shaped, maybe from being such a wide tire sqeezed onto a narrow rim. I have run these tires for over a year with no problems though. There ya go, my .5 cents.
 
Youll fe fine with 33's and 2.5" lift although if you seat a full car you might experience rubbing and when the wheels fully turned on the trail you might rub them as well, 4" will give you a better clearance but for eample i have rubbing on my truck when on the trail and the wheels fully turned but the again i dont mind minor body damage. BTW i went to 4.11 gears my dicks are heavy tires


Lookd good DK5:waytogo:
 
my '85 came with 3.08's as "stock gears".......it sucked bad with 33's. you may have 3.73's in there and you'll be ok with that for a road truck. i'm doing 3" and 33's pretty soon and i have 3.73's. i'd prefer an 8" rim for 12.5" wide, but the alloys work for lots of people. i'd be a little more mindful of air pressure though, use chalk for long life......go with a 2" lift, less complications for a mostly driving rig. fwiw
 
I just ordered a set of BFG AT's 33x10.50r15's today. Decided on the 10.50's for a few reasons.
1: less rolling resistance, as I use my K5 as a multi-purpose vehicle(DD, Tow rig, Toy) and need better mileage, while not giving up much in the off-road capability.
2: Better fit for my stock aluminium rims( I hate the balloon look)
3: Price $163 a piece.
 
trustyrusty said:
I just ordered a set of BFG AT's 33x10.50r15's today. Decided on the 10.50's for a few reasons.
1: less rolling resistance, as I use my K5 as a multi-purpose vehicle(DD, Tow rig, Toy) and need better mileage, while not giving up much in the off-road capability.
2: Better fit for my stock aluminium rims( I hate the balloon look)
3: Price $163 a piece.
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i hope you'll post pics when you get her all shod up........good choice. i remember how heavy my 35" AT's felt for my DD weekender truck.
 
just wondering would there be that big a diference between the 10.5" and lets say 11" or 12" widths..resistance, drag all that stuff.
 
I really doubt you would notice any difference between 33x12.50s and the current 32x11.50s, assuming similar style of tire (weight, tread pattern...not something like 32" street tires vs. 33" Boggers).........there will be some differences in braking and acceleration but it's whether or not the seat-of-the-pants dyno can notice it or not.

I ran 32x11.50's with a 4" lift back in the day (already had the tires) and personally thought it looked a little weird with the smaller tires.
 
Only thing I'd be worried about was the front tires' sidewalls hitting the drag links but I believe those 15x7's have half an inch less backspacing than the 15x8 Rally's did. That should keep the tires off of the steering gear.
 
AJMBLAZER said:
Only thing I'd be worried about was the front tires' sidewalls hitting the drag links but I believe those 15x7's have half an inch less backspacing than the 15x8 Rally's did. That should keep the tires off of the steering gear.
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Not sure of the backspacing on the rally's but my 15x8 alum. rims 3.75"bs w/32x11.5r15's have no clearance issues on the stock susp. Gettin 33x10.5r15's put on as soon as the tire shop gets them in. will post a few pic angles and maybe some articulation shots when I get my baby home.
 
cool, please post front,back and side views of the 33x10.50,s maybe i will go that route too instead of 12.50's
 
Factory 15x8 Rally's have 4" of backspacing. The 15x7's have 3.5" if I have it correct.

I know my 16x8's with 4" of backspacing and basically 32x10.5R16 tires have not a lot of clearance between the sidewall and the drag link. Still, might be workable. Haven't measured much to see actually. Need to do that to decide my next size up.
 
I'm getting 33x12.50xR15 BFG M/T KM2s installed tomorrow as well. Since my rig is completely stock, seeing DK5's stock rig (which is damn nice, btw) makes me breathe a little easier.
 
AJMBLAZER said:
Factory 15x8 Rally's have 4" of backspacing. The 15x7's have 3.5" if I have it correct.
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Yes, but I do not have stock alloys mine are 15x8 factory were 15x7 (guess I should have clarified) they have the fake rivets. RPO code says it came with the alloy wheels but these aren't them(Look like these--pic is not of mine) No name brand or #'s but do say "made in china"(A/R Outlaw knockoffs) they were on it when I bought it.
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stillyz said:
seeing DK5's stock rig (which is damn nice, btw)
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bot0611 said:
Lookd good DK5:waytogo:
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Thanks d00ds :thumb:

I will also say that I do notice some minor rub noises when leaving steep parking lots with the wheels at full turn. So if you are going wheeling you will probably notice some rubbage, especially when flexing the suspension. I don't do any heavy wheeling, although some mild snow wheeling and I don't have any trouble.

If you use wider rims with no lift, you will have a lot of rubbing no doubt.

Pic whore time (I have to get some more recent pics with the new paint.. soon hopefully) :pimp:

DSCF3579.jpg


BTW these tires (Kumho AT's) suck in the snow and ice. I ended up getting some 31" trailcutters with studs and the performance both on the highway with icy/slushy conditions and offroad is phenomenal. No comparison IMO.
 
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