Rim options for stock tires + suspension?

Gagerr

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I'm horrible with all the crazy numbers that come with rim/tire setups, (off-set, width, etc.)

I'm wanting to know of any rims out there that can be run with stock suspension and tires on my 2017 civic si. (or what to google to find the exact size that will.)

I'm also okay with them protruding a bit. Would that be negative offset?

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They can poke out from the fender with even positive offset. It depends on how wide the wheel is you will be using. The more negative an offset, or in our case compared to the OEM wheel, the lower the positive number toward zero the offset is, the more the face of the wheel will have been moved inward on the rim toward the center of the car.

I know different wheel specs seems overwhelming to learn, but it will help you actually decide what wheel is best for you if you can correlate the different sizing together with the pictures you look at of wheels. For instance, 18 in radius x 9.5 width wheels are usually running a lower positive offset from our OEM wheels (OEM: +50, new wheel: around +35 or lower). This kind of set up with give you poke, or wheels that come out of the fender a little bit. 9 in width on the same 18 in wheel usually sits flush with the fender (or in line with it) and will usually have an offset between +30 and +50. Our OEM wheels are 18 x 8 with offset +50.

Depending on what wheel you get, you then have think about the tires size. OEM is 235/40r18.those fit an 8 in wheel. If you go bigger width wheel, you gotta have a bigger tire to not sacrifice drive quality. But that also means you have to clear the wheel well as well. I’ve seen people running up to 265 tall tires in their cars on stock suspension with wider 9 -9.5 in wheels, but just keep in mind you may rub when you hit bumps with a tire that tall. I personally run 9.5 in wheels with stretched 235/40 tires, but that is because I’m on lowered suspension. Even with the tire being lower profile now, the extra width still rubs on the fender liner when I hit dips at speed since it in now extending past the fender. If possible in your case, don’t stretch your tires if you don’t have to, it will lessen the quality of the ride and make the road imperfections more noticeable.

The most common “yes it will fit” answer is 18 in radius x 8 - 9.5 width wheel with 235-255 tires on OEM suspension. Keep in mind if you plan on lowering the car in the future though.

With that in mind, decide what look you want and then choose the sizing. On stock suspension, you will clear everything with a bigger width wheel. Some people even go 19 in radius wheels and are fine. Unfortunately there is no easy google term to this process. You just have to find wheels you like, then look at the specs, and then compare them to what other people are running on their cars. If someone else has the same specs on their different wheel and it works, then it’ll probably work for you. Just going to have actually do some more learning in your end.

Good places to start for just looking at wheels is tire rack, auto anything, discount tire, etc. Then try fitment industries to see if anyone has put that specfic wheel you like on their car. Fit industries lists what kind of suspension the person used, tire sizes, and what kind of car, as well as if it rubs, and pictures of the set up. It can usually give you a good idea of how it’d actually look on a car.
 

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https://www.civicx.com/threads/factory-wheel-size-offset-and-weights.1636/
https://tiresize.com/wheel-offset-calculator/

Since you have an Si, your stock wheels are 18x8 with +50 offset; and your tires are 235/40-18.

I'd suggest sticking close to the same offset to retain the excellent handling you already have.

When I wear out the OEM tires on my Sport Touring (same wheel specs as yours, just different paint), I'd like to get 245-width (preferably 245/40 for a little extra bump protection).
 
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Gagerr

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So what does each of the three numbers in the string "235/40-18" mean?

Also, regarding the +50 offset stock; if I wanted them to stick out more would i get it closer to zero or higher than 50?
 

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So what does each of the three numbers in the string "235/40-18" mean?

Also, regarding the +50 offset stock; if I wanted them to stick out more would i get it closer to zero or higher than 50?
The first number (235) is the tire width, so in this case 235 mm. The second number (40) is the aspect ratio of (tire width) :to: (tire side wall height). In this case, the side wall is 40% of 235 mm, or 94 mm tall. The last number will always be the diameter of the wheel the tire is supposed to go on, in this case 18 in wheels.

Regarding the offset, go lower than 50 toward 0 to get them to stick out more (if the wheel is the same width as OEM or more), and higher than 50 to bring them back in toward the center of the car.
 


BarracksSi

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So what does each of the three numbers in the string "235/40-18" mean?
235 = width, in millimeters;
40 = the aspect ratio of sidewall depth to tread width. It's a weird way to measure this part of the tire, but you'll get used to it. In this case, the sidewall depth (measured from where it holds the rim to where it reaches the ground) is 40% of how wide the tire is. Smaller number means a thinner, lower-profile tire, with sharper response but less bump absorption.
18 = Inner diameter of the bead. Basically, the diameter of wheel that it's made to fit onto.

Also, regarding the +50 offset stock; if I wanted them to stick out more would i get it closer to zero or higher than 50?
To stick out more, you'd use a lower offset number.

Here's how it's measured: The difference between the wheel's outer centerline and the inner surface where it mounts to the hub is the offset. In this wheel, the surface of the wheel that actually presses against the hub when mounted is 50mm outboard of the centerline of the tire.

A zero-offset wheel would have its center exactly even with where it mounts to the hub.

The problems with changing offsets can be loading the hub bearings in a way they're not designed to handle, or rubbing the tire against the edge of the fender, or rubbing the inside edge of the rim against the suspension, or changing the scrub radius of the front wheels (the difference between the pivot point of the steering axis and the center of the tire), etc. Unless you modify the suspension geometry to match, you can make a car handle demonstrably worse by picking wheels with specifications that are too far out of stock.
 
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Gagerr

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But if you were to go to 9 inch wide wheels, wouldn't you need to compensate on the offset?
 

BarracksSi

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But if you were to go to 9 inch wide wheels, wouldn't you need to compensate on the offset?
I'll talk this through (mostly for myself, because I've not considered this exact question, believe it or not) --

So let's take two wheels, one 8" wide and the other 9". Both have an offset of, say, +50.

That means that the inner face of the mounting surface is 50mm away from the centerline of the wheel, or the center of the tread. This applies to both wheels.

The difference is, on the 8" wheel, each half of the wheel is 4" wide; on the 9" wheel, each half is 4.5" wide.

(still thinking... aha!)

Ok, here's why you might have asked that question:

The offset is not measured to the outside face of the wheel that you can see while the wheel is on the car. It's measured to the inside face, the unpainted part (usually) that touches the hub and brake hat.

A wider wheel with the same offset as a narrower one will have slightly more of a "dish" effect -- because the edge of the rim will be farther away from center while the mounting surface of the wheel stays in the same place.

Let's create a fictional wheel that's just one inch wide but, for some crazy reason, still has a +50 offset. It has just a half-inch of width on either side of wheel's centerline, right? But the inside face of the wheel sticks out 50 millimeters -- and, in this fictional case, would even stick out past the edge of the rim where the tire sits.

(does this make sense? I royally suck at drawing, and haven't googled around for diagrams)
 

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There is a lot of good info for beginners in here but my 2 cents is this. I find it best for people who don't understand fitment to just go with a popular size known to work for this car with stock tires. The most popular I see is 18x8.5 +35 . Those will be flush and not poke out at all, the stock tires will have no noticeable stretch (meaning proper size), common size so lots of styles to choose from, and work even when lowered without rubbing. If your wheel choice has a less aggressive offset (anything higher than 8.5 +35) example 8.5 +45 those will fit. Anything with a lower number example 8.5 +25, may have rubbing issues.

So in short google "18x8.5 +35 wheels" Find what you like and be happy.
 

civichero1

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I have 18x8.5 +35 on stock suspension. Like people above mentioned it is the perfect setup. tires wont wear too fast, no rubbing, flush look, and MUCH lighter than the factory wheels (unless you get something really bad).
 


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If you're dead set on keeping the stock wheel size and offset (I am because if anything axle/suspension related goes bad under warranty Honda can't blame the wheels) , the Enkei PF01 does come in 18x8 +50 offset and weighs 17.8 lbs (measured by me). My set should be going on this week. You MUST buy Enkei's brand hubcentric rings (75mm to 64.1mm) since aftermarket ones won't fit. I did not know this beforehand.
 

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You MUST buy Enkei's brand hubcentric rings (75mm to 64.1mm) since aftermarket ones won't fit. I did not know this beforehand.
Good word. I didn't know Enkeis had a different centerbore than usual.
 

CyberCT

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Good word. I didn't know Enkeis had a different centerbore than usual.
This seems to be PF01 specific. I had RPF1s for my old RSX and those wheels had the beveled edge for aftermarket hubcentric rings. The PF01s are a 90 degree edge from mounting face to cenerbore that goes over the hub.
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