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Discussion Starter · #1 ·
Hi, im shopping for new wheels for my Koup. Ive been looking for the Xxr 522 or 518 and their "wheel expert" has recommended 18 x 8.5 +30 wheels for my Koup. I wanted to know if any of you has installed wheels on this offset or if its ever possible to use it without any crazy alignment or rubbing issue, any answer will be really appreciated :)
 

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Our wheels are 17 x 7 with about a 42 - 45 offset. You'd be adding at least 1.5 inches to the outside, which I believe would impact the fender the next time you drove over a set of railroad tracks. It may not clear on the inside either. Bad advice.
 

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Our wheels are 17 x 7 with about a 42 - 45 offset. You'd be adding at least 1.5 inches to the outside, which I believe would impact the fender the next time you drove over a set of railroad tracks. It may not clear on the inside either. Bad advice.
Actually, the specs for our wheels are +48mm offset. You could get away with anything +38 to +58 when using stock tire sizes. If you are up sizing to 18" what tire size are you using, is the overall diameter larger than stock? If the diameter is much larger and they stick out past the stock size, you could very well be hitting the fender on bumps.

What size tires is he recommending?

Look at this comparison I did http://members.shaw.ca/westernAvenger/forte/18%20inch%20tire%20size%20comparison.pdf and see what www.rimsntires.com said, quote "Package will stick out 28 mm (1.1'') farther. Make sure that you have enough room under the fender. If not, consider narrower tires or higher offset."

It would be hard to go much narrower on the tire with an 8.5" rim, you might want to consider consulting a different "Tire Expert".:cool:

According to WheelsNext, XXR 518 Black Wheel Rim at WheelsNext.com , they are not recommending anything wider than a 7" rim an the Fotre, although I thing you can go to a wider tire and rim as long as you keep the offset high enough to keep the tire behind the fender. Just my 2 cents.

Cheers.
 

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Gotta also keep in mind that moving a tire's center 'inboard' to go wider while avoiding the fender may end up bumping into your strut, or contact with the inner wheel well while turning. We ran into this a LOT while playing with fitments on '09 Sorentos last summer...
 

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Discussion Starter · #5 ·
I was told to use not wider that 215/40/18 tires, im still confused.. what are ideal specs for our Koup which will look agressive and still not get past by the fenders?
 

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215 tires aren't nearly wide enough for a 8.5" wheel, even if you could get the wheels to fit the car. Whomever told you not to go above 215 is also feeding you a line. You can go as wide as you want if 1) it's the proper width tire for the wheel you're using, and the whole setup clears the fender lip and wheel well liner / strut. My Mazdaspeed 6 comes stock with 215/45/18 tires and it was wearing 235/40/18 on Mazda RX-8 rims when I got rid of it. No rub, no issues. There's plenty of room under the Forte for a wider combination, if the offset if right and it's not TOO wide.
 

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thanks for the answers guys.. still cant find a wheel that i like and its Forte specs

I have 18x8.5 47 offset wheels with 225/40-18 tires. However I do have the sedan. The look is all about what you want. I like my look with the setup I have, but I also like what others have done with their Fortes'


 

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Discussion Starter · #9 · (Edited)
Those looks really nice Bradleytri! Do you guys we can get away with 18 x 8.5 +40 on a Koup?? (Using BIgE's guide it will only stick 0.5" farther) im really considering the Xxr 521 wheels i love em
 

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hmmm are u guys sure it's +48? i took my wheels off today and the stock 17x7 wheels are +50 offset.. according to what was inscribed into the rim...
 

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Those looks really nice Bradleytri! Do you guys we can get away with 18 x 8.5 +40 on a Koup?? (Using BIgE's guide it will only stick 0.5" farther) im really considering the Xxr 521 wheels i love em
OK, I did some research; here's what I've come up with, one thing at the time:

OFFSET: Your choice of XXR 521 18X8.5, 5X114 bolt pattern, 40 offset wheel (great looking wheels, by the way :cool:) sticks out to the outside between 26/32 of an inch and 29/32 of an inch from the OEM stock 48 to 50 offset wheel (8/10mm for offset and 12.7mm for added width). Hang on to that, we'll come back to it a little later:

WIDTH OF RIM/TIRES: The recommended rim width for your choice of tire, (225/40-18) is 7.5" to 9.0", 8.0" being ideal so your 8.5" wide XXR 521 is fine for that tire size and 215/40-18's recommended width is 7.0" to 8.5" so that would work out also. The total section width of that 225/40-18 tire varies between 9.1" and 9.3", depending on brand so for comparison let's take the middle at 9.2". The total width of the OEM Goodyear Eagle LS 215/45-17 is 8.4". Therefore the additionnal width of the 225/40-18 tire over the OEM 215/45-17 tire is 0.8" but only half of that, 0.4" or 13/32 of an inch, sticks out on the outside. Let's add that to the 26/32 of an inch from offset above for a total of 39/32 of an inch or 1 inch and 7/32 further to the outside from the OEM stock 48 offset wheel (and 42/32 or 1 inch and 10/32 for the OEM 50 offset wheel).

That's significant and the only way to know is to mount them on the car, rub chalk on the inside of your wheel wells (fender) and do relatively low speed turns at full steering wheel lock both sides (because you're reducing the offset from stock i.e. more to the outside, I don't think fitment will be a problem on the inside of the wheel/tire). If no chalk on the rubber, it fits :D.

Generaly, if you mount tires on rims, you can not exchange tire nor rim. If the guy selling you the wheels is garantee-ing the fit, go ahead, you got nothing to lose. If he's not garantee-ing the fit, it's a potentially expensive experiment...

If chalk on the rubber, it doesn't fit :mad:.

One possible solution is 'rolling" the inner fender (with a specially designed tool that attaches to the hub on the car) to fold back the inner fender lip (from personal experience, that'll get you an additionnal 3/32 to 7/32. Don't forget to heat up the inner fender before rolling or the paint will crack and you'll have corrosion issues later... again, personal experience :() The other solution is widenning the wheel wells which means cutting, welding, filling, sanding, painting, $$$$$... You get the picture...:eek:

So, how much do you love those XXR wheels??? :eek:

I agree that they're bitchin'; I very sincerely hope they fit 'cause she's gonna look really great if it works out (you'll share pictures, right?)

******
 

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you can fit any wheel you want.. if it came down to it youd have to pull the fenders but thatd be a really aggressive fitment.

i want to go with an aggressive fitment though. im coming from the stance scene and buying my Koup isnt gonna stop me, will be pretty sweet to have the first aggressive stance Koup :)
 

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Discussion Starter · #13 ·
Sorry i didnt follow up this thread after last reply. I changed my mind on those Xxr 521 as i started trying some friends wheels and found out 8.5 width virtually wont fit correctly on a lowered Koup without major modification to wheel wells and or fenders; im not into that on a new car anyways. So finally following Gringos steps i bought some Xxr 941 18 x 7.5 +42 and changed things a bit for a custom look.

before


After (crappy phone pic sorry)


Removed the red stripe and painted bolts "annodized" style blue which happened to match Corsa Blue very good. Now im waiting to have some free time to install Eibach Springs and slam those wheels on the koup. Will bring a pic of the final product really soon :)
 

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hi, I need help from the wheel size calculation experts
I have a Forte Koup SX 2010.
I have ordered the H&R lower springs (1.3"/1.2")
I want to change my wheels for 18" and was leaning toward increasing the width to 225/40R18. From what I can read a few posts above it seems like 18x8.5 47 offset wheels with 225/40-18 will fit on a Forte sedan. Can someone help me figure out if the same would be true for a Koup? I am aiming for 18x8 wheels, not 18x8.5, and after looking at many wheels, my favorites all have an offset of 45. Is the 3 mm difference too big, or can I safely install 18x8 45 offset wheels with 225/40R18 tires (considering the car will have been lowered with the H&R springs)? I have no idea whether 45mm instead of 48mm will be too big a difference.
 

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Ew... that may be too many variables and you may end up stuck with the dreaded "try it out" answer. Install the lowering springs, then test mount ONE tire on a rim and see if it fits. Run the suspension through it's full travel, turned both ways, and see if it'll work. Then try it on the other front tire (you'd be surprised in what will fit on the left won't fit on the right) and repeat the test. Then try the rears (although I seriously doubt a problem here with the design of our rear suspension).

Only after you have test fit all four corners with the same wheel, should you mount the other three, and install. This way you'll be able to return the three for full credit, if it doesn't work out for you. Most places will NOT accept a mounted tire or rim for return.

This is something you'll be well served to take to a proper wheel shop, and let them play with.
 

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hi, I need help from the wheel size calculation experts
I have a Forte Koup SX 2010.
I have ordered the H&R lower springs (1.3"/1.2")




I want to change my wheels for 18" and was leaning toward increasing the width to 225/40R18. From what I can read a few posts above it seems like 18x8.5 47 offset wheels with 225/40-18 will fit on a Forte sedan. Can someone help me figure out if the same would be true for a Koup? I am aiming for 18x8 wheels, not 18x8.5, and after looking at many wheels, my favorites all have an offset of 45. Is the 3 mm difference too big, or can I safely install 18x8 45 offset wheels with 225/40R18 tires (considering the car will have been lowered with the H&R springs)? I have no idea whether 45mm instead of 48mm will be too big a difference.
Searching updates...1/7





Agree with KIATECH on the testing method. But I think we can get a good feel for the fit potential by looking at the numbers one issue at the time:

TIRES: I understand your desire to "... increasing the width to 225/40R18. ..." but in actual fact, the difference between 215/40-18 (which btw is the perfectly matching 18" tire size for the Koup, baseline being 195/65-15 from the Forte) and 225/40-18 will be negligeable in terms of traction/handing and in terms of visual cosmetics. So if you're willing to concede just a little on that point, it helps us to deal with...:

18x8.5 vs 18x8.0 vs 18x7.5 and 45 offset vs 48 offset: The Koup SXR wheels from the dealer's R accessory list are 18x7.5, 48 offset and are fit tested on the car with the Eibach springs and 225/40-18 Yokohamas. Going to 8.0" wide rims, 45 offset adds a total of 9.35 mm to the outside (6.35 for the added rim width and 3 mm to the outside for offset) from the baseline Koup SX 17x7.5 w 215/45-17 (assuming you're mounting 215/40s. 225/40 adds an additional 5mm to the outside).

My gut feel would be that it would fit no problem; I'm basing this opinion on the amount of space left between the tires and the inner fender on my own Koup SX (Eibach springs, 18x7.5 48 offset x 215/40-18).

Using bradleytri 's own Forte sedan as comparison (a few posts above; 18x8.5 47 offset w 225/40-18 which, from the pictures, clearly fits otherwise it wouldn't be on the road...) he's added 13.7 mm total to the outside and remember his is a Forte sedan; the Koup has slightly wider fender flares which would provide a few mm additional space so...

Based on all this, I think that 18x8.0 45 offset w 225/40-18 will fit. (but 215/40-18 would be a safer bet... 'cause that's 5mm less bulk to the outside you'd have to deal with...)

Good Luck!

******
 

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Thanks ******, that's exactly the type of response I wanted, with all the numbers, measurements and all.
I don't feel very strongly about putting 225's on the car, my main goal is getting nice wheels, after that, if 225's will fit then all the better, but if not I'll just stick with the 215's... nice wheels are my priority, larger tires would just be a bonus, but if they don't fit then so be it and I'll get 215's.
 

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OK I've investigated a bit more, and seems like the stock wheels on my Koup SX are 17x7 +50 offset, and not 17x7.5 +48 offset.

So (assuming I correctly figured out how to calculate things myself based on ******'s post) getting the 18x8 +45 offset would actually give a 17.7 mm difference sticking out to the outside compared to stock wheels.
However, I had first indicated that I was aiming for 18x8 rims, but 18x7.5 will do as well, so that would decrease the difference to 11.35 mm.

However, isn't the width of the rim irrelevant? In my understanding, if my new wheels+tires set do not fit, it is the tire that will rub against the fender, not the rim, so it is the tire width I need to select carefully, not the rim width, correct? Unless I buy wheels like 18x9 that are wider than the tires, which I won't do, the rim width is irrelevant, no? The rim offset however is important, as it affects how much the tires will protrude on the outside.

Is my reasonning correct or am I overlooking something?
 
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