I just ordered a set of front and rear brakes to do a 5 lug conversion on a Duramax. Has anyone else done this before? We're wanting to run a 15" wheel to open up tire options. I'm wondering what you guys might suggest for offset/backspacing if you have already done this conversion or have any knowledge on the subject. I'm not even sure what width we will need. I know the front WMS width should remain close to the same. The guy that makes the brakes said they take a factory hub assembly and drill a new pattern into it to do the conversion on the front, and they make a new hub out of aluminum on the back.
5 lug conversion and 15" wheels
- Thread starter JoshH
- Start date
What are you putting it on, I saw it once in a hotrod pickup where they reused part of the frame and used the front end but it was 2wd. I would think going to a 15 would open up less options
I’m by far someone that knows jack squat about this, but I’m assuming the 5 lug conversion lessens the size of the hub/rotor assembly? I’d think with 15s unless it’s been reduced a bit you’d have issues with clearance with any backspacing/width combo. I believe James posted something about a similar kit, and hondarider (can’t think of his name) chined in and said he had just done a conversion of some sort. If it’s the same one, maybe he will chime in? Otherwise just ignore me. 
I would think your problem would be clearing the brakes. 16's are a tight fit around the calipers.
ok drag wheels is a different story now it makes sense. so are you running brakes for like a half ton, the only thing i could see being an issue is the caliper size.
I would think the back spacing or clearance issue would only come into play with the rear wheel/tire combo, what I mean is on a 2 WD Drag Truck I would think you would run as narrow a wheel as possible in front which would typically have a 3 1/2”—4” back spacing which typically doesn’t even get to caliper from the mounting surface of the wheel .
2wd or 4wd josh? fronts easy if its 2wd.
rear will take some cleaver wheel setup and some caliper grinding. see if you can find a wheel with a reverse drop center (inner narrowed part of the wheel that lets you put the tire on easier). usually they are at the back of the wheel and causes the rubbing issue. if you can get one where its at the front of the wheel and tapers or goes back up to bead size to the back, it may just take some grinding of teh caliper and 2-3" back space or something. I know my old 2000 1500 GMC rear calipers needed a good hit with the grinder to make 15's fit but those were smaller rear brakes than we have.
front on a 4wd will be another story. you dont want a bunch of back spacing and you want that front tire sucked in as much as it can be. i dont know if there is any way to get around the large caliper up there without a whole new rotor/caliper setup.
rear will take some cleaver wheel setup and some caliper grinding. see if you can find a wheel with a reverse drop center (inner narrowed part of the wheel that lets you put the tire on easier). usually they are at the back of the wheel and causes the rubbing issue. if you can get one where its at the front of the wheel and tapers or goes back up to bead size to the back, it may just take some grinding of teh caliper and 2-3" back space or something. I know my old 2000 1500 GMC rear calipers needed a good hit with the grinder to make 15's fit but those were smaller rear brakes than we have.
front on a 4wd will be another story. you dont want a bunch of back spacing and you want that front tire sucked in as much as it can be. i dont know if there is any way to get around the large caliper up there without a whole new rotor/caliper setup.
I don't know how I missed updating or responding to this, but I think most of you guys misunderstood my original post. I'm not asking how to clear 15s. I already ordered a brake/hub kit that will clear 15s. I was asking more about wheel size and backspacing, but it's all good. I contacted a wheel manufacturer called HoleShot Performance Wheels out of Florida, and ordered a set of their 3 piece R3 wheels. The guy I talked with was very friendly and helpful, and he said they would put a rush on the order to make sure we had them in time for a test and tune event we are trying to make it to. Not my next issue is picking a tire. He wants to stay with a DOT tire just in case he wants to run a class that requires that, but I'm trying to decide between a radial or a standard wrinkle wall tire. I know radials are faster, but from what I understand, they require a lot more track prep to hook than a bias ply construction tire. Anyone played around much with both on a 4wd diesel and have any good advice on what to go with? Looking for something around 30" tall that will fit on a 10" wide wheel.
And for those who are curious, this is the wheel we ordered (without the $300 bead lock option, that may come later though). We ordered a 15x10 with 5-7/8" backspacing.
And for those who are curious, this is the wheel we ordered (without the $300 bead lock option, that may come later though). We ordered a 15x10 with 5-7/8" backspacing.
I’ve run both and have had better luck with the bias ply , with them I’m able to run the truck full tilt fuel plus NOS so far versus the Hossier DR2s wouldn’t hold full tilt fuel only , kept airing them down and they still spun and moved in my rims as well . With a 15” wheel and 30” tall tire that should give you plenty of sidewall to absorb the shock on launch . Bias Ply better all around plus I believe they can be had in DOT versions as well.
I’ve run both and have had better luck with the bias ply , with them I’m able to run the truck full tilt fuel plus NOS so far versus the Hossier DR2s wouldn’t hold full tilt fuel only , kept airing them down and they still spun and moved in my rims as well . With a 15” wheel and 30” tall tire that should give you plenty of sidewall to absorb the shock on launch . Bias Ply better all around plus I believe they can be had in DOT versions as well.
What size DR2 vs slick were you running? Either option I'm looking at would be roughly the same size. The radial I'm looking at is the Mickey Thompson ET Street Radial Pro 315/60R15. I haven't quite decided what bias ply tire we would want to try yet. Like you said, both would have quite a bit of sidewall, so it won't be apples to apples like most 8 lug bias ply vs radials. Most of the radial tires diesel guys run have a rather short sidewall or are overall a shorter, narrower tire than what we are looking at. The truck currently has as set of Mickey Thompson ET Street R drag radials on an 18" wheel and usually runs mid to low 1.4 60' times at 6k lbs. We are looking at being well under 5500 once this thing is all back together (maybe closer to 5k), and I expect the weight reduction and wheel/tire change should really cut some time off that once we get the suspension dialed back in.
I'm excited to get them here. They look pretty sweet, and I can't wait to see them on the truck.
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I was running 325/45/18 DR2s versus now I’m running 16” wheels and tires and my tires are 31.75” OD versus the 30.25 OD on the DR2s so I’m in agreement with you not really 100% apples to apples . Sounds like he is already 60’ing very well with the DRs though . Mine did well with them too just not when I wanted to improve on it and run it full tilt . Subbed for some pics of the truck with new wheels and tires . Good Luck Josh
Run the bias plys Josh. they will continue to work well the lighter you go. They are more forgiving to variables like track prep and temp and so on. just be prepared that the truck will feel much more squirrly on the big end so the driver has to pay attention and not make huge steering inputs if its not going the way he wants. Even on radials hes gunna notice this "numbness"
That's kind of the way I'm leaning. Part of me wants to run a bias ply because I know they'll be more consistent and won't be so sensitive to the things you mentioned and a less experienced driver that may not be able to launch as consistently as a radial will require. At the same time, a less experienced driver is part of the reason I am considering the radial because of a bias ply's tendency to be less predictable in handling on the top end. At the end of the day, I tend to agree with you that a bias is the way to go, but once it is all said and done, I think it will come down to cost and availability as the main contributing factors.
totally understand. you are already a few steps ahead getting more sidewall so either way will be an improvement!
Will the thin sidewalls be an issue on the bias ply with the weight of the truck . I’ve heard if the vehicle is too heavy and your running a 2 ply wrinkle wall it can turn into an issue with wadding the tire too much and running over the wad . Just food for thought. The ones I run are stiffer sidewalls .
thats more of an air pressure issue imho. you get "tire shake". a high hp car coming off the trans brake can hit the tire with more torque than we can coming off the foot brake.