Wheel backspacing confusion (1 Viewer)

[Bax454]

Hello, I have tried some searching, but keep stumbling over my thoughts and what I think is right. I want to maintain where the current location of the outside tread is, but going to a different tire and a 7" wheel.

Details:
Currently running FZJ80 factory wheels
From what I read they are 8" , 4.5" backspacing (and 0 offset/centerline)
Current tires are 255/85R16 (BFGs) (so 10.03" tread width)
I have recently ordered a new set of rubbers, which are 9.50" x 36.5 (Q78's)

If I loose an inch of wheel (from 8" to 7"), do I simply loose 1" of back space on the wheel. Now given I also understand I am losing .50" of tread width, but I may factor that in one I get my brain working. I drew this up, trying to figure it out:



Trying to maintain the 'greenish' line on the left side of the image

So say same tire, I go 7" wheel with 3.5" back spacing out to put the tread in the same location?

And furthermore, If I go 9.5" thread from a 10", I need to reduce the backspacing by another .25", Ultimately being a 7" wheel, with 3.25" of back spacing?????

 

[murf]

Trying to find that exact wheel with a large enough center bore will be difficult. Most toyota truck wheels will have the same 4.5 backspacing so will stay further inside wheel well unless you utilize spacers with them.

 

[Bax454]

If I cannot find some sort of Toyota wheel, I will end up buying a steel wheel which I was assured I could find one that will fit the center bore. Eitherway, are my thoughts correct about the back spacing?

 

[murf]

yes, I agree, I would lose the 1 inch and go 3.5 on the backspacing otherwise between the skinny tire and the 4.5 it will look very inset in the wheelwell.

post pics when you mount them up!

 

[Bax454]

Thanks @murf - I suppose I just had to draw it out and ask the all knowing MudMembers. The only other factor is the narrower tire and might lose another .25". Exciting news, the tire store just called and said they had some burly tires come in I will post a pic for you.

 

[Fast Eddy]

It is not easy to find 16" steel wheels with a 3.5" backspacing. You can order them and wait from a couple places. I went with 7x16 with a 4" backspacing. You can usually use a 1/4" spacer without getting new lug nuts, so you're within 1/4".

Why not keep the wheels you have and run the new tires on them? Are they 15"? My 15" wheels don't fit over my 80-series rear calipers without a spacer.

The tread width is not going to be narrower on narrower wheels. The overall width at the sidewall will be a little narrower.

 

[Bax454]

Did Toyota ever make a 16x7 with a 4" BS? I would consider that - I haven't looked yet. The tread width won't change with wheel width, I understand that, but it [new tire] is narrower than my current tire and want the tread right at the de-flared fender. The TSL (SAM-53's) specs a wheel size of 6.5-8" so, it would be acceptable. However, I am concerned with a bit more bead protection and seem to be pretty rough on tires. I simply chose 7" as a happy medium, and I would also consider a 6.5" but it starts exposing calipers to the dangers of off pavement driving.

16" wheels/tire ('93 FZJ)

Thanks for your input.

 

[Fast Eddy]

Did Toyota ever make a 16x7 with a 4" BS?

Not that I know of. The 16" split rims are 3.5" BS, and the first 16" rims are 4.5" BS. If they'd have made one, I would've gotten some, but they weren't available, so I got the cheap dash8 black steel rock crawler rims with round holes. They look ok. Someday I want a set of 16x8 with 4" BS that take hub caps. It's pretty low on my list for now.

 

[Cruzerman]

Are split rims a viable option in the states? Or are they more trouble than they are worth?

 

[Fast Eddy]

Using tubes and finding someone who knows how to change tires safely on split rims are two good reasons to not use them.

 

[Bax454]

Haven't decided on wheels yet, but my daughter would rather just make a play gym out of these: