guy with insomnia and dyscalculia needs help with offset and spacers
 

this is probably the stupidest thread ever created here, but I'm just really confused and drunk on sleep deprivation now.

was fiddling around with the 86 wheel fitment calculator thing, and I was planning on adding spacers to my 18x7.5 wheels to make them look slightly less tragic. now, I had always assumed that adding a, say, 20mm spacer to a 48 offset wheel would basically translate into 28 offset, correct?

so if I got a et48 7.5 wheel, subtract half an inch, 12.7mm, to match the original offset correctly, THEN minus 20mm from a spacer, I'd get a a 15 offset rounded up, and the wheel poking all the way into the other lane of the road? except the fitment calculator gives me the same result for 7 and 7.5 wheels both. am I missing out on something here?

tl;dr, 18x7.5 ET48 wheels sunken way into the fender, what length spacers should I get

What do you want it to look like?
Stick a ruler on the wheel/tire and figure out how much further out you want them.
Say you wanted the 18x8.5 +35 look.
18x7.5 +48

Difference-
-13mm of offset
1inch of width(1/2inside half outside 1/2= aka -12.7mm of offset)
=25mm bolt on spacer.

On the stock 17x7 +48, everyone gets 20-25-30mm bolt on spacers. Your 1/2 inch of extra width(6mm inside/6mm outside) is close, being 6mm wider on the outside. So I'd suggest 25mm spacers.

your post cleared it up for me, thanks a lot, didn't realize the width was divided between in and out on the wheel, thats where the bulk of the confusion came from

I'd prefer them to poke as much as possible, without hitting the fenders. and when I'm getting around to lowering it this summer, I won't go any lower than 0.4-0.7 inches

I got some real pokey 17x9 for winter wheels right now, but its my summer 18's I'd need these spacers for. gonna go take some rough measurements later today when I replace my brakes

thanks again man

You won't hit fenders, if anything you will rub the rear bumper tab.
What tire size are you running on the 18's?
What are the offsets of the 17x9's? My guess is +20. Do you want your 18's to look like that?
Pics of the two sets of wheels mounted?

Go look at pics of 18x8.5 +35(25mm spacer) or 18x8.5+40(20mm spacer) and see how they fit.

Most springs start at around 1inch drop for looks. RCE yellows are 20mm drop.

You're welcome. Post some pics. :D

http://imgur.com/ghs6Whd

current setup

http://imgur.com/vi2C7kW

and the buyers remorse 18x7.5 rota GRA

looking for a coilover I can match OEM ride height with currently, heard some people say bilsteins can do that, I'd have to do some more research.

the 18's are on 215/40 now, but I'm gonna do 225 potenzas this summer.

Agree with swarb's suggestion.

I use 18x9.5 +45 as a reference for max flushness without rubbing on 265/35R18 tires (some tires that run wide like MPSS may rub the bumper tab depending on your camber/height/spring rate). The spacing difference between 18x9.5 +45 and 18x7.5 +48 is 28.4mm. So you could use 25mm or 30mm spacers.

People go further out with 18x9.5 +40 or +38 wheels but at that point they need to run slightly narrower (stretched) tires and/or roll their fenders. In that case you can fit a 35mm.

Click my sig to see pics of how 18x9.5 +45 look (currently only in my rear with 18x8.5 +42 and 3mm spacer in front, older pics show 18x9.5 +45 square). And there's plenty of 18x9.5 +40 or +38 fitment pics on this forum.

Get Bilstein B6 with stock springs or B8 if you want lowering springs. With very minimal research you will find it will definitely fit. I push to avoid coilovers if you don't need adjustability because they tend to make noises that springs/struts won't.

Make sure you get extended studs. With such a thick spacer, there's not much thread for your lugs to bite on and you don't want to end up like my buddy.

I'd have to get coilovers im afraid, reason being that I really can't go any lower than an inch at all. very bad roads over here, combined with a catback that currently hangs 9cm above the ground. so 20-30mm lowering springs are a no go. plus I need TUV certification on all parts to keep my registration.

looking at H&R or eibach spacers with TUV certification, they're supplied with studs. expensive, but I guess you shouldn't be greedy when it comes to parts like these.

I'll be a little bit conservative and go 20mm front and 25mm rear. its a temporary solution anyways til I can find a set of 17x9 +35 RPF1 from someone who wont rob me blind on shipping costs'

edit: car looks absolutely fantastic by the way

Do you require adjustability? If not, stock springs/struts will still fit, Bilstein B6 is an upgraded strut matched to stock springs. These will be higher quality than most coilovers for street use IMO.

BTW STI offers 15mm lowering springs.

not really, been looking at KW V1 and monotubes that only adjust height and little else. I'd just like to return to stock ride height if need be without pulling an all nighter in the workshop, the winters up here in the arctic circle can be savage, and I daily this car all year round.

https://www.japanparts.com/parts/detail/41317
https://www.japanparts.com/parts/detail/45137

price is pretty damn reasonable, and I love the STI pink, I'll make a note of them

What are offset are the 17x9s? Is that too much poke for you?
Do wheels need to be tuv approved?
Depending on the cost of the bolt on spacers, they could cost as much as one rpf1. I say save up and sell your current set and get what you want. Can you to take a holiday to another country and bring them back?

my winter wheels are about perfect, another 5mm in the rear would be nice though. I believe they are et35, might be wrong.

been trying to sell my 18's, not a single bite even though I've listed them at 40% of the original price, wheels alone. gonna order one and one RPF1 in the future. the shipping and import tax on each of them are still a pain in the ass. if I had gone through and ordered them from oakos like I would, I'd have paid another 900+ usd in shipping and import alone. to make things harder, rpf1 in 35 are next to impossible to find, especially in gold.

edit: theoretically, every single modification to functional parts you make will have to be TUV approved, but I don't think anyone really cares about wheels. far as drivetrain and suspension parts go though, its extremely strict. imagine not having a single turbo available, and some 2-3 meh superchargers to chose from.

You would need 30mm spacers to match the 17x9+35.
Can you do grey area import taxes? Like used? Or as aluminium? Or go for A holiday WITH the car on a boat and install outside of the country? Do you need to pay taxes on a gift? Hahahah

best I can do is ask the seller to lower the value of the package, but I'd still have to fork out a big sum for shipping.