Sorry guys I am to lazy to search right now.

18x9 +38 Front
18x10 +45 Rear

Thanks Guys

Also is a 255-40-18 tire ok on the 10? For the time being.

 

i know the rears would fit, the 255's on a 10" i wouldnt do it but that doesnt mean it wouldnt work. rynberg would be the one to know that. and i believe the fronts would work as well.

 

38+ wouldn't work; maybe with coilovers? You should wait for a suspension guru to get on. Mahjik told me 18x9+40's would be a tight fit, i'm going to run rsr's/tokicos with rolled fenders.

 

The tire will fit. Most 255/40/17 tires are spec'd for 8.5-10" wheels generally.

Use stock offsets as your standard and do the math. 1 inch = 25.4mm
assume stock 8" (8*25.4 = 203.2mm) wheel with 50mm offset (offset means distance from center of wheel to mounting point, also known as frontspacing)
an 8" wheel with zero offset will have 4 inches (101.6mm or half the wheel) from the mounting point to the front bead
an 8" wheel with 50mm offset will have 51.6mm frontspacing (101.6mm minus 50mm)

Now look, all you have to do to figure out offsets is figure out how much you need to move the mounting point from the center to obtain near-stock frontspacing.

use the search function and figure out what type of backspacing you can get away with.

I find a 10" 42mm offset wheel to be a good standard to go off of for frontspacing without lip rolling and backspacing figuring about a pinkie's width between the back of the rim and the trailing arm.

It's not too tough, you guys should be able to field these questions now and take the load off of rynberg.

 

I'll tell you guys a secret.... If you look up the 255/40/18 tires on tire rack then click "specs" the you will see the manufacturer's recommended rim widths.

 

Yea I figured that out after I posted this(couldn't remember what site had it)

 

Hey wanklin, keep in mind that we are talking about nominal width when we say16x8, 18x10, etc. When you're calculating front and backspacing, you need to keep in mind that the nominal width is from bead seat to bead seat (the inside part of the wheel where both tire beads sit) - the actual width of the wheel will be wider (you then have to add the 'lip' on either side of the wheel).

Unfortunately, there are no standards for the actual width beyond the nominal (bead seat to bead seat) width, and will vary from manufacturer to manufacturer. However, this is only really of concern if you are are trying to calculate mm's worth of clearance (such as trying to calculate 2mm's worth of clearance from the wheel to the trailing arm). I have not seen a drastic difference in actual widths, for the same given nominal width of different wheels.

 

Yes I realize this but that is a good point, I just didn't want to further complicate things, but I guess they should know ;o). I guess I should also add that you should look up the nominal width of the tire and add a fudge factor of probably 2mm or so when making your calculations to account for nominal width variances.

It's good that you brought the rim width point up because a lot of people probably overlook this. I'd say most rims are roughly one inch wider (give or take 1/8" or so) than their stated width due to the bead widths not being included. Real world example: My "8" OEM 99specr is actually 8 + 7/8 inches. Ofcourse their could be larger variances out there but that seems like a good rule of thumb.

Like you said, if it's a game of mms then one must account for every bit of rubber on that tire or the largest tire that you think you might use in the future in order to pick the right offsets.

To make things easy just forget the rim width and use tire width alone when calculating the offset and spacing. ;o) All you need is one good set of data that you can base your calculations off of.

 

18x9 +38 will not fit up front, 18x10 +45 will fit fine in rear

255/40 is wrong tire size, it's a full inch too tall. 255/35 would be the correct size.

 

He's saying that 255/40 is too tall at 26" because you should try to stay closer to the stock diameter of 25"

 

Thanks guys. My friend has these wheels on his Supra and he wanted to know if he should post them here and on the Supra forums. I probably could have figured it out because my 18x8 fronts are +38.

If anyone is looking for Blitz Z2's for their Supra let me know.