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Options to stop 33x12.5" Tyres rubbing leaves.

Posted: Sat Oct 11, 2008 4:35 pm
by mike_nofx
Hey all.

I have 33x12.5" BFG Muds fitted to my wt Sierra, but they rub the leaves on full lock. They only rub at the back of the leaves tho, not front.

Just want some advice on what my options are for stopping this.
Heres the options i see:

Change Rims - Rims are 15x7" Sunnies, which i believe may be F100 rims. Offset is approx -16mm From my calculations. Should i have a wider offset? Will wider offset rims cause other issues (like guard clearance)

Change Tyres - I need new tyres soon, so i guess i can get a more narrow tyre, but for a 33" muddie to fit a 15" rim 33x12.5" seems to be all thats avaliable from most manufacturers. in 16" rims, 33x11.5" is more common. Wonder why?
Will a 32x11.5" Stop the rubbing? (Not wanting to go any smaller really)

Adjust bump stop - Is there a bump stop for steering? I noticed on my 100 series that it has a bolt head which hits a plate, Looks adjustable. Does the Sierra have something similar (I looked but cant find it)

Wheel spacers - Legal issues aside, Are there any other issues with fitting these? I understand there is more stress on bearings etc, but is it worse than fitting bigger offset rims? Are they safe?

Whoever comes up with the best and cheapest idea wins!

Thanks
Mike

Posted: Sat Oct 11, 2008 5:13 pm
by Gwagensteve
7" rims with 12.5" tyres - you need to sort that - those tyres won't be happy and it will be making the spring contact worse because of all the sidewall bulge. Run 8" -24 speedy rims and space your steering. The rearmost knuckle seal retaining bolt on each knuckle is the steering stop. you can fit a longer bolt with a nut to act as a spacer or weld a little plate to the axle.

Steve.

Posted: Sat Oct 11, 2008 5:30 pm
by want33s
If you really want BF muds then get 33x10.5's.

Jas.

Posted: Sat Oct 11, 2008 5:41 pm
by mike_nofx
Dont want BF's.

Overpriced, and to me just look like an agressive AT tyre.

Considering either Silverstone mt117 sports, Federal Couragias, and possibly Maxxis Big horns.

Trying to stick to as close as i can (or below) $1000 for a set of 4.

Thanks for the advice gwagsteve. Will look into the rims and/or bump stops.
With the 12.5's on 7" rims, i thought it would be ok. At least it shouldnt pop a bead? Will some tyre shops refuse to fit a 12.5 to a 7" rim?

Thanks
Mike

Posted: Sat Oct 11, 2008 6:00 pm
by Gwagensteve
Yes. Techncially, the minimum rim for a 12.5 is 8.5, but 8 is commonly fitted. 7's are way under the odds.

Don't 100% believe the narrower rim it will keep the beads on better. The steep angle between the rim and the tyre will start to pull the bead away from the rim even though it's hard against the bead.

Steve.

Posted: Sat Oct 11, 2008 7:26 pm
by brendan_h
ive got this problem as well. will it cause harm? also with making a bump stop. you weld it onto the axel so it hits the knuck felt seal retaining bolt? use a rubber stop?

Posted: Sun Oct 12, 2008 6:31 am
by Gwagensteve
Yep. the little plate has to be angled so the bolt on the knuckle hits it square.

Steve.

Posted: Sun Oct 12, 2008 10:21 pm
by lockdup
I've got 34" swampers on a 7" flipped rims, tyre is 10.5 wide and it car has a pritty wide stance. no rubbing what so ever. try a 10.5" tyre or offset rims

df

Posted: Mon Oct 13, 2008 10:51 am
by Pyrotech
i run 32x10.5 simex pedes on a standard 5.5inch sierra rim, with a custom offset of -47 and they dont scrub on the springs... they come close, but clear by about an inch.

no i know the rim is too narrow for that size tyre, but i have had no issues with rolling the bead or spinning the rim inside the tyre. this is just my expirence

try a 10.5 is my suggestion