Scion202

****UPDATED****

Updating this first post kept cutting things out, I guess something has changed with this forum.
Anyways to fix that I've turned this helpful post into a full blown article with pictures and colors, Enjoy:

Idiot's Guide to Wheel Fitment Basics

Best,
KidJustin

****UPDATED****

I've seen many threads on here asking the same question "Will it fit?" So this should be a guide to finding out whether your new wheels will most likely fit. Remember that if you're SUPER low then things will change. This is for stock height.
-1" front and rear should work as well, we'll adjust this post as we get some real life posts.

First watch this video for a short tutorial: www.youtube.com/watch?v=qwiqAr2bI-I

As you know the width of the tire is given in inches while the offset is in millimeters. To bring all this in the same units, I will be using centimeters

1 cm = 10mm
2.54cm = 1inch

I'll use stock wheel as an example

So here is the formula for finding out how far from the hub will the back/inner part of the wheel go in(BACK SPACING):

width(inches) x 2.54 = width in centimeters
center line of the wheel in cm = width in centimeters/2
center line in cm + offset in cm = distance from the hub to the wheel's inner side(BACK SPACING)

To find out how far from the hub will the face/outside part of the rim stick out(FRONT SPACING):

Just subtract the offset from center line

Example using stock wheel:

18 x 7.5, offset +39 (offset of the wheel will almost always be positive)

Width in cm = 7.5 x 2.54 = 19.05 cm
Center line = 19.05/2 = 9.525 cm
Hub to inner side = 9.525 + 3.9 = 13.425 cm (Back space. I dont know what the maximum fittin back space is)
Hub to face side = 9.525 - 3.9 = 5.625 cm (btw, to be flush in the front on TRD springs, this should be roughly 7.2cm and 8.2 rear)

BTW, (BACK SPACING) + (FRONT SPACING) = Wheel Width....obviously haha

Bottom line for most purchases you need to know the back spacing and its just CENTER LINE + OFFSET!

For "Flushness" you need to know the Front spacing which is just CENTER LINE - OFFSET

Tests:


NOTE1: Just remember to take it with a grain of salt. Since what usually rubs is the TIRE and not the RIM. Tires usually are wider than the wheels!

NOTE2:When you're dealing with smaller diameter wheel then you will need LOWER offset to clear the caliper

NOTE3: Wheels with huge lips may not clear calipers

NOTE4: Make sure to keep the same rolling diameter. USE THIS FOR CALCULATING ALL THE TIRE SPECS: http://www.1010tires.com/tiresizecalculator.asp

NOTE5: Updating this first post kept cutting things out, I guess something has changed with this forum. Anyways to fix that I've turned this helpful post into a full blown article with pictures and colors, enjoy!

Idiot's Guide to Wheel Fitment Basics

__________________

KidJustin

too much math!

but i love it! great job...i nominate for a sticky

and i will revisit this after i drop my car...i will definitely need some consultation after that haha

Scion202

haha read the bottom line then

just make sure ur in centimeters.....thats it!

Scion202

little spread sheet, hoping the rays would fit but it seems its literally may be t0o much by a millimeter!

Back and Front in the top row are short fort Back Spacing and Front Spacing

KidJustin

Whoa that excel kicks butt! No LEDs but I'm still impressed.

N yea I saw the bottom

WellesleyScion

So 18x10 +30's will fit... nice. Yuri, wanna toss in 18x10 +25 to see how those will compare?


EDIT: nevermind, I see you have the 5mm spacer on the right, that will equal out to my spec request.


Ok so 18x10+25's will sit 0.643700787 inches further out than mine do, looks like that will be my next wheel size :D

Scion202

with that MEXI-FLUSH you will most likely have to roll some fenders in the front haha

Scion202

some updates:



Matt(1stOne) runs 9.5 with 45 offset! He says it will not clear the stock front caliper though. However it will depend on the wheel, the spokes on his wheel dont come out to the out edge of the rim, his is more like "deep dish"(spokes are inside the rim)

Regardless, his rim has a HUGE back space and it still fits!
I guess now the bottle neck is the front spacing(rolling fenders or not) and clearing the calipers!

For Sean there it will depend on whether its a deep dish wheel or not to clear the calipers



Normal wheel:



Deep dish:



1stOnes':



So as u can see even if the offset is really low ~+20 or +25, with deep dish wheels you may still grind against the calipers!

KidJustin

i dont think there are any test subjects yet...but hypothetically speaking...

how would the drop effect wheel width/offset?

like how about a 2 in drop or a 3 in drop?

Scion202

the wheel would be cambered, as a result you will worry about having enough back spacing. Howevera(on stock height), when you go over big bumps then your wheel will camber in as they are lifted towards the body of the car and for a second it will simulate as if you were very low.......
SO if people that fit with HUGE back spacings dont just drive on a straight road and have a fair deal of big speed bumps or pot holes that they drove over and nothing rubbed then technically being low is a good thing because you wont have to roll fender because the tire will be tucked under it!

the problem is, we dont know the relationship between camber angle and the drop to actually see if this works

Scion202

new update with ZeroEye's wheels setup:




His setup suggests that front spacing of 9.5cm! will fit without rolling fenders in the back ON TRD SPRINZZZ!!!



So with Alex's and Matt's successful fitments, we can technically fit a 10.2" wide wheel with offset of +35 on TRD springs


Just remember to take it with a grain of salt. Since what usually rubs is the TIRE and not the RIM. Tires usually are wider than the wheels!

dm1336

Thanks for this. The offset thing still has me confused but I will eventually learn it.

I made stupid decision and bought 16" winter tires on steel wheels so I am looking to change the rims and get some 16" alloy ones that fit the tires and also clear the calipers. These calculations will help make the search slightly easier.

Scion202

latest:




these calculations are for 18" wheels

so it will be a bit different for the 16", just make sure that spokes are bent aggressively aways from calipers and dont buy anything that looks like the spokes are inside the wheel

TCnightrider

iTrader: (2)

ok so did i do this right then since you said it will be different for what size of wheel you are going to do
they are xxr 526
17x9 25 17x10 20

9.0x2.54= 22.86 22.86/2= 11.43 11.43+ 2.5= 13.93 11.43- 2.5= 8.93

10.0x2.54=25.4 25.4/2= 12.7 12.7+ 2= 14.7 12.7- 2= 10.7

Scion202

yeah looks right however i just googled the wheels and it looks like they have a huge lip which means you could have caliper clearance issues. BUT with such low offsets i think it should be fine, as long as the lip aint half a wheel in size.

also with 10.7 front spacing you will have to roll fenders. depending on how low you are, you may have to raise the ride or change camber. or try to get as narrow tires as safety allows

is that the wheel?

Scion202

if it dont clear calipers then you could use 5mm spacers but that would create such a low offset that the handling could get real crappy.

If they dont clear the calipers I'd forget about the wheels

When you're dealing with smaller diameter wheel then you will need LOWER offset to clear the caliper

KidJustin

has anyone tired it with bigger rims? 19in maybe

or any advice with larger diameter rims

TCnightrider

iTrader: (2)

i figured that i would have to role front and rear and pull the rear a little, but i am going to have 205/40/17 front and 215/40/17 rear for tires. i found a couple pixs and looked at them and i hope it will clear everything, if not i will make it till they do fit.
i was going to do 17x9 front and 17x10 rear

Scion202

ill be putting 19's on mine

it will be all the same as long as the rolling diameter stays the same!

USE THIS FOR CALCULATING ALL THE TIRE SPECS: http://www.1010tires.com/tiresizecalculator.asp

yardleyTC

iTrader: (1)

im looking to get some 18x8s to fit the stock tire, the offset of my is a 43 mm. The lip is 1.5 inches. is this going to be an issue?