Ford Power Stroke Nation banner

Pics 38 x 15.5 x r 20 4.5 backspacing

14K views 38 replies 10 participants last post by  Monster_NRG 
#1 ·
Hey guys,

Truck is in the sig but will 38 x 15.5 x r 20 with 4.5 backspacing work with a 99.5 with 6" of lift.

Have 37 13.5 r18 now really just worried about the 4.5 spacking and 15.5

Also any pics with this setup would help or close to it.

Thanks,
 
#7 ·
Does it just rub the leafs at full turn? You have 3.8" bs, this bs is 4.75. Would this help any?
 
#3 ·
Thanks for the heads up. I guess its 4.75 bs if that makes any difference. Do you have any pics for reference?

anyone else?
 
#8 ·
You think so smart ass! Tell me what else you know. Sounds like we can all learn a lot from you and your 472hp :bowfast:
 
#13 ·
If you run a 10" wide rim with 4.5-5 BS a 38"+ x 14.5"-15.5 " tire will rub the leaf at full lock out. You need to go either less BS or go up to a 12" wide rim. The wider rim with fix BS moves the tire out and also reduces the overhang of tire.
My buddy has an 8in procomp lift on his 2000 f250 with 38 15.5 x20 mtz's and he rubs leafs and fender.he has already smashed both fender corners since installing them as well as tore up the sidewall lugs from rubbing on the springs.This is with 4.5in back space.The spring rubbing would be fixed as tarm said if the wheels were wider because it would have less tire bulge.Don't know about the fender rubbing with a wider rim.
This is not what i wanted to hear but need to hear. thanks

Does anyone have any pics or links to pics showing this size rim tire combo? or damage caused?:doh: Guess i am getting blinded here by a sweet deal for some really good looking rims and tires. damn
 
#10 ·
If you run a 10" wide rim with 4.5-5 BS a 38"+ x 14.5"-15.5 " tire will rub the leaf at full lock out. You need to go either less BS or go up to a 12" wide rim. The wider rim with fix BS moves the tire out and also reduces the overhang of tire.
 
#11 ·
BMac, Do you think this is just because of the 3.8 bs. If you had a bs of 4.5 would that fix the problem. But then maybe rub the leafs.

Tarm, Thanks for the info. This is what i am starting to hear. Do you think i would have any other problems other than rubbing the leafs. Such as hitting the bumper or fenders?

Thinking about getting these tomorrow and would hate for them not to work. I can deal with them hitting the leafs at full turn. Just wonder how bad it would be? Think it would be so bad i would have to not turn all the way or could turn all the way and have it rub just a little? I know it all just depends but trying to get a good idea of what i'm getting myself into.
 
#12 ·
My buddy has an 8in procomp lift on his 2000 f250 with 38 15.5 x20 mtz's and he rubs leafs and fender.he has already smashed both fender corners since installing them as well as tore up the sidewall lugs from rubbing on the springs.This is with 4.5in back space.The spring rubbing would be fixed as tarm said if the wheels were wider because it would have less tire bulge.Don't know about the fender rubbing with a wider rim.
 
#14 ·
You can not fit that wide of a 38 on there with 6in lift without rubbing.You have to trim or probably cut to make them fit.I would either add some lift or go down to 36 15.5 wide.Now if you want to go skinny I had 38.5in boggers on mine with no rubbing anywhere but they were skinny.I now have 36x14.5in tires on it same lift and they rub the inner fender and fender corners on inclines while turning or bumps while turning.I could only imagine what 38's would do.
 
#15 ·
Do you have an all spring lift on there now?It wouldn't be that bad to add 2 inches on there if its all spring now and a taller block in back.
 
#16 ·
What bs did you have chappy also what would i be looking at to add 2" of lift. I would be getting a great deal on these tires and rim and hate to pass but sounds like i might have to
 
#17 ·
2in hanger shackles,front driveshaft spacer or get yours lengthened,adjustable track bar.Rear depends on what you have now.Pro comp makes a kit to go from 6 to 8inches and I think its $500.Comes with everything for the kit.You should technically get longer shocks as well but you would probably be ok.
 
#18 ·
I think pro comp is whats on there now. Do you know what the height should be from the center of the lug nuts to lets say the top of finder to make sure its a true 6 in kit? so for 500 bucks it would come with everything needed ds spacer shackles blocks

know anyone else runnin the set up im tryin to
 
#19 ·
I am running what I believe is a 4.5" lift now. I am not really too sure because the info on the lift was not available. The rear is stock and My front sits about 3" taller than the rear. I have got a 5" backspace on my 12" wide wheels. The tires are 38x15.50R20's and when I turn sharp or compress one side as I go through a ditch or something similar they rub the springs as well as the plastic liner near the bottom of the inside fender. I had to cut the front corners off the bumper and they have not touched since. My tires are getting bald and when they are replaced I will go with either 37x13.5's or smaller.
 
#21 ·
Thanks, makes me feel somewhat better about this deal. Have any pics of your setup ?

Also why not get some blocks for the rear?
 
#22 ·
Got them. Hope to get them on tomorrow. Let you guys know if it fits and hoping to get some good pics.
 
#24 ·
Well put the front left on and it looks like its going to work without any triming or cutting. Im sure its going to rub the leafs but we will see. Working on taking the flares off because at full turn and a bump would not be good for them haha. Just hoping to not find any suprises under there or when i take the chrome off.

Will get some pics after I clean it up a bit. Things dirty.


Also working on getting my chip sent out for retuning for the 160cc/80% injectors going in sometime this week or next.

Thanks John @ cowboy diesel for making all this happen. Couldnt have a better brother. :redspotdance:
 
#25 ·
They all fit fine, ended up trimming the bumper a little to give more room. Tires ride great, not to loud either. I am very happy with the way they turned out. Only place where it rubs is at full crank on the leaf springs, which is a lot better than what we thought would happen. Will have pictures added up tomorrow after it gets a good bath. Do anyone know the best tire cleaning product?
 
#30 ·
Do you already have the wheels themselves? If not go get some 12" wide rims. That will take care of the leaf rubbing with under 5" of BS. You make get s little at full lockout but adding a bit of weld tot eh knuckle stop or drill and tap a hole into it and screw in a bolt. It will not take much.

As for the fender rubbing you only have 2 choices to not rub:

Go up or trim.

For me I do not want any contact no matter how far I am compressed and wheels turned in any direction. If there is ANY contact IMO then they do not fit. Now you can live with tires that do not fit to varying degrees. There are different levels of tires that do not fit. But the fact remains if they touch, at all, in any situations the they do not fit and should not be said they do without qualifying the statement.
 
#31 ·
Got a good deal on these is the only reason for the size. If i was going to buy this size tire new i would have got a 12" rim. I would have been just as happy with a 37 x 13.5 x 20.

We are just saying they fit on there and you can drive around without it messing anything up. Not saying its the best fit in the world and couldnt be better. It does rub the leafs but a lot of trucks with just 13.5 do so im not too worried about that.

What is the best way to much sure the lift on there is a true 6" and not a 6.5 or something. Don't want to tell everyone it works for a 6" if i have a little more room.
 
#39 ·
Thanks, it just keeps getting better and better!

Glad they are not off to much to be an issue with DD. So they are on a 10 wide rim and are 38x15.5 with a 4.5 backspace and they just barely rub @ lock out? Youa re actually turning the wheel to lock out and not just stopping when you feel the grinding? I have yet to see a single 15.50 wide tire on a 10" rim with 4.5-5" backspacing on a 99-04 leaf sprung SD that does not rub bad at full lock out. The bumper is usually a big hit and you have taken care of that. At hard turn and hard compression I would be careful of the back corner of the fender well.

You know the cut outs seem extreme but the amount you actually cut is really not much. Only the bumper and the lower back edge really get much taken off. You mainly only follow the flat part of the wheel flare. With that you can fit a 41" with 4" lift. Only leaf spring contact which to can be completely resolved.

BTW what tires are these. They may not be as wide as some others such as the MT which are the widest I think I have ever seen. A true 15.50 IMO.

38x15.50x20 kuhmo kl71 with 20x10 black kmc rockstars bs 4.75
 
#38 ·
Glad they are not off to much to be an issue with DD. So they are on a 10 wide rim and are 38x15.5 with a 4.5 backspace and they just barely rub @ lock out? Youa re actually turning the wheel to lock out and not just stopping when you feel the grinding? I have yet to see a single 15.50 wide tire on a 10" rim with 4.5-5" backspacing on a 99-04 leaf sprung SD that does not rub bad at full lock out. The bumper is usually a big hit and you have taken care of that. At hard turn and hard compression I would be careful of the back corner of the fender well.

You know the cut outs seem extreme but the amount you actually cut is really not much. Only the bumper and the lower back edge really get much taken off. You mainly only follow the flat part of the wheel flare. With that you can fit a 41" with 4" lift. Only leaf spring contact which to can be completely resolved.

BTW what tires are these. They may not be as wide as some others such as the MT which are the widest I think I have ever seen. A true 15.50 IMO.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top