Proper backspacing for Method Racing 305 wheels

[tommyg]

I'm looking to put NV 305 8.5 wheels and 285/75/17 BFG's on my truck that's cut and has flares. I'd like for the tires to fit close to flush with the flares, but I'm not seeing anything consistent on proper backspacing to achieve this. I did see something about someone using 1/4" in front and 1 1/4" in the back, but that doesn't seem to make sense unless I'm totally missing something (definitely possible). I'm currently running 33 x 12.5 with no spacers (can't remember the wheel brand). They fit pretty flush, but I'd like a bit of a narrower tire. Going to call the NV tech team tomorrow, but welcome input from anyone with experience and recommendations.

 

[Yeller]

If you like the flush part of your existing tire and wheel combo, Pull a wheel and measure the back spacing, need to know wheel width too. We can help you get there, just need more information.

 

[tommyg]

If you like the flush part of your existing tire and wheel combo, Pull a wheel and measure the back spacing, need to know wheel width too. We can help you get there, just need more information.

I need to dig up my current wheel brand. Measured (roughly) the backspacing with the wheel on and it seems to be (again roughly) equivalent. Don't know the wheel width though, somebody may recognize these (and they will hopefully soon be for sale ). Tire size calculator tells me that the new tires would be roughly 1.3" narrower than the current 33's.

 

[Broncobowsher]

Usually all the wheel information is on the back of the spokes. Take the wheel off and look for any information on the back side of the wheel.

 

[tommyg]

Or I suppose I just could have swung open the spare tire carrier in the first place . Current wheels are actually 15x8, offset actually looks to be 4". So I'm guessing, with the new tire/wheel setup of .5" wider wheels, .75" more backspacing ,and 1.3" narrower tires (or more given the slightly wider wheels), I'll likely need at least a 1" spacer (more realistically 1.25") do I have this right? Are there any safety concerns at 1.25"?

 

[Madgyver]

same wheels here on yellow77.
I installed 1.5" adaptor/spacers up front and 2" adaptor/spacers on rear.
I pressed in longer studs on rear axle for proper thread engagement with lugnuts on 2" spacers. I had to trim a little off the studs up front.

Firebronco has FW axle swap so no spacers used with my old similar sized wheels

 

[tommyg]

same wheels here on yellow77.
I installed 1.5" adaptor/spacers up front and 2" adaptor/spacers on rear.
I pressed in longer studs on rear axle for proper thread engagement with lugnuts on 2" spacers. I had to trim a little off the studs up front.

Firebronco has FW axle swap so no spacers used with my old similar sized wheels

I guess angle is everything. Pic looks as though the front tires are about 4" outside of the fender flares, the rears inside the flares.

 

[ksagis]

One thing to consider is if your brakes have been changed - for example, I have Chevy brakes on front and Cadillac on back which resulted in WMS being 1.5 narrower in back.

What is offset of the wheels you’re thinking of? Looks like 0mm offset and 4.75 BS?

(I’m guessing OEM had same WMS front to back since sales literature proudly stated wheel track was same front to back and fairly sure all wheels were same)

Rough math and tired, will check tomorrow - you’ll give up half of 1.3 sidewall width which is 0.65” and also 0.25” of wheel extending out, so all things being equal, that would be 1” narrower. But wheel is wider which will buy back some. I’m guessing 3/4 to 1” inch spacers would give similar placement to your flares.

These the specs on what you’re looking at?

BS is measured from outside of wheel lip versus wheel width datum

 

[tommyg]

One thing to consider is if your brakes have been changed - for example, I have Chevy brakes on front and Cadillac on back which resulted in WMS being 1.5 narrower in back.

What is offset of the wheels you’re thinking of? Looks like 0mm offset and 4.75 BS?

(I’m guessing OEM had same WMS front to back since sales literature proudly stated wheel track was same front to back and fairly sure all wheels were same)

Rough math and tired, will check tomorrow - you’ll give up half of 1.3 sidewall width which is 0.65” and also 0.25” of wheel extending out, so all things being equal, that would be 1” narrower. But wheel is wider which will buy back some. I’m guessing 3/4 to 1” inch spacers would give similar placement to your flares.

These the specs on what you’re looking at?

BS is measured from outside of wheel lip versus wheel width datum

So many things to consider!! Yes, those are the wheels I'm looking at (3rd from the left on the top row). My truck does have brakes that were changed under previous ownership. I believe they are power drums from a similar era f150, but not exactly sure. I don't think I'd have any issues with the rear being narrower though as they are pretty equal right now. I'm guessing my best bet may be to just put on the wheels and decide on spacers after the fact.

 

[ksagis]

Had some coffee and looked at my math again, look's right to me if current wheels are 8 inch wide with 4 inch BS.

Your plan to put them on and go from there should work out fine. Just check radius arm clearance at full turn etc since without spacers, you'll be inset approx 1 inch.

 

[Broncobowsher]

Just to save you later. When trying to convert between backspacing and offset, it isn't that easy. You would think that an 8" wheel with 4" of backspacing would be 0 offset. It isn't. The 8" width is measured inside the wheel at the bead contact surface. The backspacing is measured at the outside of the rim lip. An 8" wheel will measure about 9" outisde to outside (8" inside to inside). So you are actually looking at a wheel with an offset of about 12mm off the true centerline of the wheel.

Want to double check that? Measure the backspacing from the wheel mounting surface to the inside of the wheel. Get your 4" Now go through the spokes or center hole and measure from the mounting surface to the outside of the wheel. It will be about an inch more.

Many of the new wheels don't publish backspacing numbers anymore, only offset. You almost need to make a table of what backspacing you will get for each width of wheel for the same offset. Or what offset to look for at each wheel width to make a target backspacing.

 

[Madgyver]

I guess angle is everything. Pic looks as though the front tires are about 4" outside of the fender flares, the rears inside the flares.

 

[67sport]

This might help

 

[tommyg]

For whatever reason, I only seem to be able to find 1.25" spacers (Spidertrax, Wild Horses, and 4WP) that work for the Bronco. Going to order the tires & wheels w/o spacers for now from TireRack, install them in my driveway, i.e. back out 5 feet from my garage, check the steering clearance and if there's rubbing (or if it looks crappy) then order spacers if necessary. Don't want the "untucked" look, but more concerned about rubbing as the tires are at least in-line with the fenders currently, if not a bit outside of them.

 

[tommyg]

Tires & wheels will be here on Thursday, will try to get them on by end of weekend at the latest and post an update. I've got a missing lock for the current lugs, but pretty sure I've got a viable workaround to get the current wheels off that I'll be testing out tomorrow am (before it gets too hot outside!) . Realized I had the current setup installed 8 years ago (yikes!), was my excuse to my wife for getting new tires. Hopefully she doesn't notice the new rims they're wrapped around lol.

 

[67sport]

One of the other members posted up a site a while back that offers all sorts of wheel adapters, not wheel spacers. Similar but technically different. Might have been @jamesroney or @Yeller
Try searching for wheel adapters, even if keeping the same bolt pattern, I think wheel adapters are what you're after.

 

[Shimmy]

do yourself a favor and get bora spacers. they are the best. it'll be beneficial to have a spacer that has a hubcentric/wheel centric lip

https://www.motorsport-tech.com/bora.html

here's an example of bora spacers hubcentric to a 77 and wheel centric to my raceline wheels. notice the lip

 

[Shimmy]

One of the other members posted up a site a while back that offers all sorts of wheel adapters, not wheel spacers. Similar but technically different. Might have been @jamesroney or @Yeller
Try searching for wheel adapters, even if keeping the same bolt pattern, I think wheel adapters are what you're after.

correct. at that much spacing you're talking about an "adapter" style spacer. my bora spacers above are bronco bp to bronco bp

 

[Brush Hog]

I am running 17x9 us Indy slots from wild horses. Think they were 3.5” maybe 3.75 bs Whatever the website says. With bfg 285/75 and they are flush or maybe 1/4” past flush. Cut fenders old school bush wacker fender flares. I think “flush” will depend on tires and flares. Flush with wh gorilla wareflares would be way different than with my bush wackers. I had minimal rub which required some minor trimming. 2 1/2 inch wh lift. Love the ride and stance.

 

[tommyg]

correct. at that much spacing you're talking about an "adapter" style spacer. my bora spacers above are bronco bp to bronco bp

Thanks for the recommendation...sorry if it's a dumb question, but what does bronco bp to bronco bp mean? I checked out the website and it looks as though they are very customizable down to the exact mm. Can you share what size you are using? I suppose the best would be to try on the wheels first and decide from there. These are the specs I took for the NV wheels...