With 20mm widebody fenders in the front, and +15 mm overfenders in the rear, what wheel specs will fill the gap without worry about hitting suspension and rubbing on the fenders? I bought wheels for the car but am now rethinking I may need to go wider to fill the gap. I have an opportunity to sell the wheels i bought (step 1 below) and swap them out for (step 2) or anything else bigger.

1) Bought staggered 18x9 + 35 and 18x 10+35. I see recommended in other threads a 18x10 + 48 275/40 can fit comfortably on coilovers + OEM body. So I would need to run effectively almost a 40mm spacer to push the wheels I bought out for an aggressive fitment? This is assuming +20mm widebody fender in the front and a inch drop from the recommended 18x10+48 spec, which returns us 25 mm of offset. This is assuming 1" = ~25mm.

2) Would a 18x10.5 + 24mm be pushing it?

I see recommended in other threads a 18x10 + 48 275/40 can fit comfortably on coilovers + OEM body. With 20mm front fenders that allows us to lower the offset approximately -24mm to 18x10 + 24, but then we we are now increasing the wheel width by 0.5 inches, so a 18x10.5 +24 would be equivalent to a 18x10 +12mm? This is assuming 0.5" = ~12mm.

3)
What offset would be recommended for a 18x11?

 

First tell us why you think you need 11s. What are you using the car for, and how much power are you making?

 

for starters, there's no reason to run wheels in the 11 and up size other than hot boi points.... which the more you have the better your life. I'm somewhere around 1800 and things are pretty good .

to answer your points though......

1) Bought staggered 18x9 + 35 and 18x+35. I see recommended in other threads a 18x10 + 48 275/40 can fit comfortably on coilovers + OEM body. So I would need to run effectively almost a 40mm spacer to push the wheels I bought out for an aggressive fitment? This is assuming +20mm widebody fender in the front and a inch drop from the recommended 18x10+48 spec, which returns us 25 mm of offset. This is assuming 1" = ~25mm.
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going to guess you meant 18x9/10+35. a 10+35 on pulled rear fenders gives you flush fitment depending on the pull. its a super poke on stock body. the 9+35 will give you almost flush fitment on a stock front fender.

2) Would a 18x10.5 + 24mm be pushing it? I see recommended in other threads a 18x10 + 48 275/40 can fit comfortably on coilovers + OEM body. With 20mm front fenders that allows us to lower the offset approximately -24mm to 18x10 + 24, but then we we are now increasing the wheel width by 0.5 inches, so a 18x10.5 +24 would be equivalent to a 18x10 +12mm? This is assuming 0.5" = ~12mm.
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a 10.5+24 has the same fitment as a 9.5+12 which is what i have on my car now in the rear. its flush with a minor pull on stock rear fenders. so a +15 over fender in the rear with a 10.5+24 will not get you the fitment you're looking for. you would need a 10.5+(10-15) or a ~10-15mm spacer and anything over a 5mm is a no go. the 10+50 sizing people are recommending is just nonsense. don't waste your time. its if you want to stuff a 275 or greater under a stock fender and look like drag car from behind. i really don't get it but style is unique to everyone.

3) What offset would be recommended for a 18x11?
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with a +15mm over in the rear, you would want an 18x11+(20-25) depending on camber and tire fitment. for the front, you are in feed gt2 territory so you will want a 9.5+15 or any of its derivatives such as a 10+(20-30).


keep in mind there are variations in wheels and tires that makes all of this math super +/- so nothing is definite. you can also "persuade" fitment with camber and minor stretching. there are a lot of variables but I'm pretty sure that's the math you're looking for. it also depends on how aggressive you want to be. lean towards the higher offsets suggested to be "safe". i haven't come across any suspension interference issues with wheel fitment in an FD in my days. maybe others have but i think you have to be VERY wrong with your wheel selection to find that out.

 

My car is going to be fitted with the GT-AD Amemiya style kit. There's no particular reason to fit 11's other then I saw it might be an option and didn't want to have the wheel fitment looking awkward. I'm looking to have a track style fitment with thicker walled tires, not thinly stretched. This is going to primarily be a fun weekend/show car with 3-4 track events a year. I have an opportunity to sell the wheels I bought with no $ loss to me and swap them out for something bigger if necessary. Horsepower goals are probably going to be low 400's once built, street port, turbo to be determined.

 

Yes, I made a typo, the wheels I currently have are staggered 18x9 +35 and 18x10 +35.

Based on what you're saying, then it seems 18 x 10 + 35 would work all around with 20mm widebody fenders in front, and + 15mm widebody in the rear. Just need a 15mm spacer in the rear. This would allow me to rotate the tires.

If I kept the 18x9 + 35 and 18 x 10 + 35 , it seems I could use them with 20mm spacers all around for a flush fitment.

 

I am currently running 18x11 +32 front and rear.
Front tires: 295-30/18
Rear tires: 315-30/18

Front fenders are stock with rolled lips, no pull.
Minor rubbing at times. This is an autox car. The fender guards at the rear of the front tires have been removed, and the inner/lower part of the fender clearanced (with a big hammer and dolly)
The rears are setup to also allow 345-30/18, on 18x12 or 18x13 wheels, so there is no problem with clearance there.

 

You are basically in the right area and can adjust with spacer widths and camber.

One really has to do the bodywork, get the ride height and alignment one wants to run and then measure and buy wheels/tires if being picky about a certain look.

Alignment will really affect what offset and width wheel you can run. Each degree of negative camber moves the outer edge of the tire inward 5.5mm.
Thats why you have racers fitting so much wheel/tire up front on stock rolled fenders- we need the camber anyways.


willtheyfit.com is a great online tool.
here I checked my 18x11 +45 offset I race with on stock rolled fenders against your proposed 18x10 +35.

Basically fits same.
so, maybe works without front camber and +20mm fenders?

Hard to say since fiberflass fenders have so much variablity. Do you shave the inner arch lips off the fronts and take the chance of them cracking if a tire touches while turning?

One nice byproduct of running wider wheels is it gets your offset closer to stock. The lower offset you run the more the car will hunt, trammel and pull side to side as you drive.