Need help choosing a 18" Rim

Brew61

Veteran Member
Jul 7, 2021
109
So I have 3.73 posi in it and set the speedo gears up for 275/60/15’s, which are 28” diameter and 10.8” wide. The fronts were going to be 235/60/15, which were 26.1” diameter and 9.3” wide.

So now that he wants to go with 18’s. I found these tires that would work. So the backs would be 275/45/18, which are 27.7” in diameter and 10.8” wide and for the front 255/40/18, which are 26” diameter and 10” wide.

Now I have to find rims. I need to know what offset will work so that there is no rubbing. The back is stock suspension the front has Ride Tech street grip coil springs. They say it can lower the car up to 1.5” but have didn’t notice a difference but they have not been driven on as of yet so not really set in.

What would be the off set if I went with any of these?
8.5 wide
9 wide
10 wide
Any help would be much appreciated

Thanks

Bruce
 

Lowend

Administrator. .a car, a man, a maraca.
Staff member
Lifetime Gold Member
Mar 25, 1999
16,811
San Jose, CA, USA
With those size tires. you want to run a
In Back 18x10 with 5.5-5.75" Backspace
In Front 18x8 with ~5" Backspace

NOW - 2nd gens are famous for having their rear axels being shifted to one side or the other by as much as a full 1/4". Before buying anything, you need to measure the rear and see if it's centered. This will determine the backspacing on your wheels. The rear can be moved by re-welding the spring pads, but this isn't a small job, and not something you want to figure out on the fly.

The 255 is in my experience a bit wide for the front of these cars. 245 will be less likely to rub
 
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G72Zed

Veteran Member
Sep 8, 2015
4,084
Canada
X2 ^^ I'm with Lowend on this. A 245/40/18 on a 8" rim with 5" BS would work nice and allow the lowered stance. Again, car to car variances do come into play.

A nice 275/40/18 on 9.5" rims on 5-5.50 BS would work, but need to check as Lowend states.
 

Brew61

Veteran Member
Jul 7, 2021
109
Thanks, yes the 245/40/18 will work to. Just making sure the tire brand makes both sizes.

so for the back rim your saying 10" wide rim with a 5.5 BS which is a 0mm off set
and the front go with a 8" wide rim and a 5" BS which is a 13mm off set

I still have to paint the inside rear wheel wells in the next couple days so when I pull the wheels I will take some measurements. This has been a complete restoration job so everything has been rebuilt back there and painted so if it is out by a 1/4" or so it will have to stay that way LOL. I don't want to even think about pulling it all apart again just to move it over by a 1/4".

Thanks again
Bruce
 

DB Z28

Veteran Member
Nov 30, 2003
671
Fond Du Lac
In the rear 10 in with a 5.5 back spacing will work. That is what i have on the back of mine. I wish i would of went to a 5.75 back spacing so i could fit a next larger tire larger than a 285/40/18 As in the front i have 245/45/18 with a 5.5 BS with a 8.5 in rim all fits well
 

Brew61

Veteran Member
Jul 7, 2021
109
Well he just sent me a picture of some rims he likes. But they only come in

18x8 with a 4.5 backspace
18x9.5 with a 5.25 backspace

Bruce

RIDLER651G1.png
 

Fbird

Veteran Member
Lifetime Gold Member
Feb 12, 2011
6,370
atlanta, ga
very similar to the Ridlers I LOVE 695's vs your 651
1663956757271.png


because I can't afford FOOSE WHEELS
1663957051619.png


made to any offset you desire.
 
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Fbird

Veteran Member
Lifetime Gold Member
Feb 12, 2011
6,370
atlanta, ga
Thanks, yes the 245/40/18 will work to. Just making sure the tire brand makes both sizes.

so for the back rim your saying 10" wide rim with a 5.5 BS which is a 0mm off set
and the front go with a 8" wide rim and a 5" BS which is a 13mm off set

I still have to paint the inside rear wheel wells in the next couple days so when I pull the wheels I will take some measurements. This has been a complete restoration job so everything has been rebuilt back there and painted so if it is out by a 1/4" or so it will have to stay that way LOL. I don't want to even think about pulling it all apart again just to move it over by a 1/4".

Thanks again
Bruce
so 10" with 5.5 BS is NOT 0 offset.....it is +13 offset
and 8" with 5" bs is -24mm offset

Zero offset would be exact center---> 10" with ZERO would be 5" Offset now in the MM world you need ANOTHER 1/2" (= 13 MM...or 12.7 mm for those who are counting)
a NEGATIVE number would be LESS than CENTER
10" wheel with 4.5" offset would = -13 mm offset
 

Brew61

Veteran Member
Jul 7, 2021
109
so 10" with 5.5 BS is NOT 0 offset.....it is +13 offset
and 8" with 5" bs is -24mm offset

Zero offset would be exact center---> 10" with ZERO would be 5" Offset now in the MM world you need ANOTHER 1/2" (= 13 MM...or 12.7 mm for those who are counting)
a NEGATIVE number would be LESS than CENTER
10" wheel with 4.5" offset would = -13 mm offset

Ok I got that off of this web site tiresize.com. They have a Offset Calculator and when you enter the 8" rim size then enter 5" BS it says 13mm off set so I guess their calculator is not right.

Any how things have changed, buyer has changed his mind. Now he wants 18's on the front and 20's on the back. I did pull the rear tires and took measurement. The diff is in there exactly even both sides are the same. Put a straight edge on the face of the drum and measured to the inside beside the shock and got 7 1/8" and outwards to the wheel well lip was 5 1/2"

So now he has picked out different rims and the front will be

U11118806145U111 RAMBLERMATTE GUN METAL MACHINED18X85X120.654.54

and the rear will be

U11120956152
U111 RAMBLERMATTE GUN METAL MACHINED20X9.55X120.655.29


Now their site specs on these rims don't make much sense, they have the bolt pattern under backspace and the 4.54 and 5.29 under offset. I am thinking the 4.54 and 5.29 is inches and that is BS.

Tires for the front so far are 245/40/18 and the rear is 275/35/20

Bruce

375a436220570c885205770db7cb6caa771b49756a673812a9fb89b71a18d0a9.jpeg.png
 
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