Gents.

I'm about to buy some new rims but I'm a little confused on the current rim size. Tires are 31. I know that. Rims are 15s. I know that. Whats the rim width I need for these 31x10.50R15LT :

What about Bolt pattern? 6x5.5? What's the back spacing? Offset? I need?

Am I missing something on the width? Is this a 10.5 inch rim or is the tire 10.5 inches on a 10 inch rim?








This is what I want from summit racing (US Wheel 94 Series Blacl):

 

Sorry, not the quickest reply but hopefully it'll help.

The 10.50 is the section width of the tread section up to where it meets the sidewall section. The tread width ends up being about 8" for 10.50 section width.

For a 31x10.50, a 7-9" wheel width is recommended. I have a set on 6" wide wheels though and it works pretty well. I've also seen them on 10" wide wheels.

6 on 5.5" bolt circle is correct for Toyota 4wd trucks.

The backspacing depends on the year/front suspension. If you have a solid front axle (pre-1986 trucks and 4runners and FJ-62/60/55/45/40 Land Cruisers), the ideal backspacing is 3.5" but no more than 3.75"

For 1986 and later trucks and 4runners and FJ-80 Land Cruisers, backspacing is usually 4.5" or close to it. Recent Toyota 4wds (about 2005+) have closer to 5" of backspacing.

Also make sure the center hole diameter is large enough. Toyota 4wds have fairly large hubs (106 mm). For alloy wheels, you need an exact fit to the hub (hub-centric). For steel wheels, the center hole size just needs to be larger than the hub (lug-centric). The current wheels in the pic are alloy so if you go to a steel wheel like the 94, you'll need different (acorn-shaped) lug nuts.

Would this truck happen to be a black Xtra-cab? I sense a Marty McFly replica in the works...

 

Well, it's grey ... and it's an 87, but it's mine. However in the next month it'll be black AND hopefully by May she'll be all restored.

I appreciate all your help! I was a bit confused on how to determine the wheel width with out having to drive to my buddies house and measure the rim.

US Wheel 94 Series Modulars are steel, so i'll have to get new nuts.

Thank you for the info.

8" rim
6x5.5 pattern
4.5" back spacing (close to it)
new lug nuts for the rims


15x8 AWESOME!

WE'RE SENDING YOU BACK TO THE FUTURE!

 

According to the website the backspace is 3.75. Is this o.k or do I have to order for a custom backspace?


http://cdn.shopify.com/s/files/1/014...odular.pdf?689


Part
94-5860

Size
15X8

Bolt Circle
6X5.5

Backspace
3 3/4

Offset
-19

CenterBore
4.28

CenterCap
C425-M

Load
1500

 

You can use 3.75" backspaced wheels on an '87. It'll just move the tires out and give you a slightly wider track. There's a slight chance that it could cause the front tires to rub if the front wheels are turned to the side and the suspension is compressed, but it probably won't be a big deal. It might not rub at all with the independent front suspension up front and 31x10.50s.

Yep, I bet Marty had 15x8s on his.

 

If I go to summit http://www.summitracing.com/search/d...th-in/8-000-in

They offer a 4.75 offset. Which should I go for?

 

If you can get them with 4.75" of backspacing (not offset) that probably work better and keep the tires in the stock geometry.

Have a look at this thread. They're using 33x10.50 tires but they're getting some rub with 3.75 and no rub with 4.75.

https://www.yotatech.com/forums/f116...-tires-141286/

This diagram shows backspacing and offset:

 

Sir, Thank you very much for all the info as well as the forums.

I've placed my order with the suggested 4.75 backspace with summit and I hope there will be no issues with my order.

 

I am looking at the same rims...did you order the 94-5860P? Did you get them yet to see how they fit? Let me know when you can.

Thanks

 

I've ordered 94-5860P. However never tried them on. I gave them to the shop to do the test fit for me. I did not have all the pieces to jack up the truck. So I personally never did the test fit.

 

Cool thanks. I'm watching your build thread so I can get my answer there!

 

Back from the dead.

Lets recap.

I got the 94-5860P (http://www.summitracing.com/parts/us...860p/overview/) which is a 15x8 rim. As I think about it, I'm going to get the matching tires as well. Goodyear Wrangler Radials.

The current tires sitting on the rims are 31x10.5x15. The tires I found for the Goodyear Wrangler Radial
are 235/75R-15 which are smaller by 2 inches. I was trying to look for 265/75-15 but didn't come up with much.

Should I stick with the 235?

http://www.discounttiredirect.com/di...5&rd=15&cs=235

 

Sorry if this is too late...I thought I check back on here and see how the BTTF truck was going.

The tread pattern of the tires on the BTTF truck look more like Wrangler ATs than the more interlocking Wrangler radials.

The Wrangler AT were once available in 31x10.50R15 but they're hard to find. They may not be available new.

http://www.goodyear.com/en-US/tires/wrangler-at

The Wrangler Radial in the 235/75R15 size may be your best bet for authenticity.