Topic: backspacing

[beyondlogic]

whats the most BS you can have on 89 IFS Truck with a 34 x 10.5 on 15 x 8 rim.

[86bobbedtoy]

the most a rim can have,
or do you mean the least b.s.

[93tonkatoy]

I believe the max for stock suspension is 4". If you have one of the bracket lifts, the common maximum is 3.75". This is because the upper ball joint is moved up to the side of the tire. You will also have to consider the amount of sidewall bulge that may put the tire too close or into the upper control arm. I have a Pro-comp bracket lift and 3.75" bs 15x10's. With 36x13.50x15's the sidewall was pressed into the UCA's. 1.5" spacers took care of that, though.

Then, you will have to watch the steering box and idler arm to see if the tire is contacting (rubbing) them.

2.5" to 3" bs should work.

[beyondlogic [OP]]

i am planning on putting longer control arms, and since that moves the rim out from the body, i have to do some kinda wider fenders so im trying to see how i can limit how much the tires stick out so that i can use the smallest flare possilble.

[93tonkatoy]

If you only install the longer a-arms, then you should be able to use the 4" bs wheels and not have too much issue with the tires rubbing the steering box or idler arm when turning sharp. Are you planning to upgrade the torsion bars too? The 34" tire may rub the fender/firewall when stuffed, unless you have a body lift.

[beyondlogic [OP]]

i have a 3" body lift and i am planning on running glass 4" bulge fenders.

[emsvitil]

I believe the 89 IFS is the same as the 86 IFS.

My 86 stock aluminum rims are 15x7 with 15mm offset = 4.59" backspacing....

A 15x8 rim with 4.59" backspacing would be 2.3mm offset.   I'd just go with 0 offset and 4.5" backspacing.

[beyondlogic [OP]]

ok thanks

[Snowtoy]

I believe the 89 IFS is the same as the 86 IFS.

My 86 stock aluminum rims are 15x7 with 15mm offset = 4.59" backspacing....

A 15x8 rim with 4.59" backspacing would be 2.3mm offset.   I'd just go with 0 offset and 4.5" backspacing.

If you are going to run 4" flared fenders w/an 8" rim you don't want a back spacing of 4.5, or anywhere near 4" for that matter .  The higher the BS, the closer in your wheels will be.  With a 4" back spacing on an 8" rim, your tires would sit 2" or more inside the fenders, and would look rather funny.   You are going to want about a 2" backspacing, and then it is likely the tires will still sit further in then the 4" flared fenders. 

If you are buying new rims, you might want to opt for 10's and not 8's.  I will post up up pics of my '90 w/3" Warn fender flares and 15x10's w/a 3" BS(IIRC).  The 33x12.50 tire are just at the edge.  I will also take some track width measurements of the '90 and my '91 that has 35x12.50 on 15x10's w/2" BS.

[beyondlogic [OP]]

well i was planning on running a longtravle kit(with longer control arms) so that would push the tires out 3.25 on each side.

but now im verablly commited to buy an 83 front axle

[Snowtoy]

My bad, i didn't realize the long travel A-arms added that much width to each side.  Were you getting the long travel arms cheap?

[beyondlogic [OP]]

i was going to make them myself.  but for the cost of flared fenders i found a solid axle so, im just going to take the plunge and go SAS.