265x35x18 vs 255x40x18

TylerTypeR

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After pouring over these threads for a few weeks I have finally decided on what wheels to order. I decided on the Enjei TS-V in 18x9.5 et40. Now I need to decide on what tire size to go with. I prefer a bit less poke provided by the 255x40, but I’m concerned the wheels won’t be protected enough and that my turn in feel will suffer due to the increased sidewall size. I live in Michigan that has pretty crappy roads. Does anyone have any experience running both tire sizes? My car is stock and will stay that way except for an exhaust at some point. It’s my daily driver and won’t see the track. Thanks for any help.
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TypeSiR

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I don’t track and opted for the 18x8.5 et38 TS-V from Tirerack. Flush and no rub on 255/40/18 pilot super sports. 8.5” (width) rims allow me to switch between 245/40/18 (large selections) and 255/40/18, depending on whichever size is on sale. Ride is great on 40 profile and has a bit of rim protection on 255 (no bulge).

Honda Civic 10th gen 265x35x18 vs 255x40x18 B8445931-2A17-48FB-9C49-53617240E5F4
Honda Civic 10th gen 265x35x18 vs 255x40x18 DFBD8458-1342-4B7A-B687-CE643C3030C6
 

ExVTEC

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Side shot please. Looks sweet.

I don’t track and opted for the 18x8.5 et38 TS-V from Tirerack. Flush and no rub on 255/40/18 pilot super sports. 8.5” (width) rims allow me to switch between 245/40/18 (large selections) and 255/40/18, depending on whichever size is on sale. Ride is great on 40 profile and has a bit of rim protection on 255 (no bulge).

B8445931-2A17-48FB-9C49-53617240E5F4.jpeg
DFBD8458-1342-4B7A-B687-CE643C3030C6.jpeg
 

TypeSiR

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Side shot please. Looks sweet.
Here ya go. I’ve already posted this pic in the wheels threads, not trying to thread cap here. :nixon:

Honda Civic 10th gen 265x35x18 vs 255x40x18 F2BF17F3-777E-480F-9EEE-8CDEFDFA128B
 


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TylerTypeR

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Honda Civic 10th gen 265x35x18 vs 255x40x18 F745DBE2-6505-4614-B413-CD3EA5889C58
Honda Civic 10th gen 265x35x18 vs 255x40x18 64298489-0F8C-49DE-9736-60EBC161B450
Thanks TypeSIR, I ended up going with the Motegi MR 924 19x8.5 et53 with PS4s in 255x35x19. I’m very happy with the way they feel and look much better in person than some of the pics I have seen on here. They look a bit more substantial in person I think. I agree that the 255 is the way to go for a street tire. The increase in traction is noticeable but I haven’t noticed any tramlining or any negatives at all. The car rides perfectly now IMO. Much tougher to spin the wheels in first and the spinning I had at the top of second is gone. I have to say I’m a bit jealous of the poke your wheels have, it’s perfect. I think the car starts to look like a dune buggy with some of the crazy offsets some guys are running, but to each their own.
 

CivilciviC

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I don’t track and opted for the 18x8.5 et38 TS-V from Tirerack. Flush and no rub on 255/40/18 pilot super sports. 8.5” (width) rims allow me to switch between 245/40/18 (large selections) and 255/40/18, depending on whichever size is on sale. Ride is great on 40 profile and has a bit of rim protection on 255 (no bulge).

B8445931-2A17-48FB-9C49-53617240E5F4.jpeg
DFBD8458-1342-4B7A-B687-CE643C3030C6.jpeg
Think 265/40R18 would be possible and still not rub, on those wheels? It would add 5mm to each side of the tire.

I see some people run 265/35, but I’m wondering if 265/40 is possible also. Or is that just a bad idea?
 

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Think 265/40R18 would be possible and still not rub, on those wheels? It would add 5mm to each side of the tire.

I see some people run 265/35, but I’m wondering if 265/40 is possible also. Or is that just a bad idea?
Id go 265/40/18 personally, thats what Im going to put on my CE28s (they are 9.5 however) coming soon (stock height). I prefer the meaty look and better grip.
 

CivilciviC

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Id go 265/40/18 personally, thats what Im going to put on my CE28s (they are 9.5 however) coming soon (stock height). I prefer the meaty look and better grip.
I too love the beefy tire look. And any sort of rim protection is always welcome. Judging by the 255/40 tires, while the rubber does extend a little past the wheel, it likely offers very little protection. Rubber deforms easy when there's 3000+ pounds pushing against it, into a concrete curb.

I keep going back and forth on what wheels I want. I'm ultimately thinking of going with a cheaper set- not that I can't afford a more premium set of wheels, but the CTR is my daily driver and it sometimes gets left out in random places where I might not see the car for hours at a time. I'm not afraid of the car getting stolen. I am afraid of having my wheels stolen, and the car left laying on the pavement. It's one thing to claim insurance on a stolen car. It's another for just the wheels.

As it stands, I'm leaning towards a set of Enkei RPF1s. Light weight. Cheap. Still leaves enough behind for me to powder coat them a different color. My only issue is they only come in 18x8.5 ET 35. I wish they came in a 18x9.5 size.

The reason I'm debating going for a 265/40R18 on the 8.5" rim is that the wider tire comes closer to the where the OEM wheel site, in terms of being closer to the suspension hub. It would likely reduce torque steer also. I think guys running the 18x9.5s don't have the same issue as guys running 18x8.5s, because of that very reason. a 9.5" wide rim allows you to get closer to OEM specs. The pic below hopefully explains what I mean, a little better- on the 265 wheel, it gets 5mm closer to where the OEM wheel sits, on the inner side of the wheel.

Here I compared a 245/40 and a 245/60 on a 18x8.5" wheel, compared to the OEM wheels:
Honda Civic 10th gen 265x35x18 vs 255x40x18 upload_2019-10-23_9-43-29




But I suppose, more importantly, here is a comparison of 18x8.5 (with 265/40) to 18x9.5 (with 255/40)
Honda Civic 10th gen 265x35x18 vs 255x40x18 upload_2019-10-23_9-50-30


the 8.5 will definitely have that beefy look to it. I strongly feel that rubbing will not occur on stock suspension, while filling the wheel well in with more rubber when using the 265/40. And while the 8.5 rim is about an inch further away from the inner side than a 9.5 rim, overall, the tire contact patch seems to almost entirely line up with the smaller wheel.

If you can fit the same size tire on a rim that is narrower, you might as well. It'll save a pound or two at each corner, by going with a narrower barrel.

The final question though- will a 265/40 even fit on an 8.5" wheel? That's the question now, lol.

Oh, and for the record- I'm anything but an expert on fitting wheels. I'm totally open to debate this setup as I'm guessing there are people thinking this is a bad idea. Thoughts, anyone?
 


CivilciviC

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Hmmm... some quick googling seems to indicate that a 265/40R18 will fit on a 18x8.5 wheel, no problem.

I've even come across a 350Z forum post where a guy was running 275/40R18 on 18x8.5 wheels for (at the time of the post) a few years, without issue, and even used them for track day events without issue.

Sweet!

Edit: Found a group of guys running 285 wide tires on 18x8.5 wheels, at the track, with zero issues. Now that's crazy!
 
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RepyT

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Few questions not sure any one person unless it’s thee Honda engineer that designed the R or the team can answer, first some background. I didn’t bookmark the post but there’s one with comments about a Ridgeline talking about the advantages of staying with OEM wheel & tire size. The gist of it was the vehicle performance is optimized with this size in so many aspects. Take that thought process that Honda carefully designed and chose the 20 series tires and 20” rims for good reasons, and optimized vehicle performance based on that standard. We (non-experts mostly) do some match calculations to closely match the overall size so speedo is accurate and to maximize performance but doubt it’s better than OEM. Questions raised:

1) I get the 20” 20 series are very susceptible to road imperfections and a decent pothole can damage fins. Depending on your locale and conditions it may be absolutronecessary to patent rim damage, a cosmetic want or appearance thing, or the belief that choosing anothe combo of wheels & tires an do better than Honda engineers. I have my doubts. Finally, the question...
Does anyone look at overall wheel weight of tire and rim compared to OEM? We seem to consider overal diameter for speed accuracy, claim triumph with braking performance using a lighter rim... but a heavier(thicker/deeper sidewalks and that usually means more flexible) tire. That may get you a softer ride but what else does it do good/bad/ugly? More questions.

2) Do people consider modes were chosen based on OEM and any resultant changes also alter dynamic performance and stresses or just that they don’t want to risk damage?

3) Rotating inertial forces are different for a smaller lighter rim, say 18” with a tire that’s heavier but same tread width compared to one with a heavier larger rim, if both have same diameter. I overall weight of tire &rim differ there are obviously feel perhaps but certainly performance changes. These can be good or bad.

4) Why do we not think past the question (so it seems) of will it fit in the wheel well without rubbing or cause too much speedo errors?

5) How is mpg impacted for similarly offsetting wheel and tire replacements if at all?

6) Does anyone think about and actually analyze airflow and the purposeful air curtain created vs impact with a smaller rim and beefier tire? Not saying there’s a huge impact here but guess what; that bigger rim moves more air that a smaller rim. There’s also the effect of more air going around the larger tire. These variables most likely don’t make a huge diff, but collectively they could impact performance and even top speed due to changes to overall vehicle airflow. I’m not saying that with lager tires and smaller rims that you’re capable of more or less speed or acceleration, just that these factors can change beyond those typically thought about as aerodynamics and wind tunnel testing is not easily accomplished. Another question related:

7) Has anyone considered larger plenum from hood scoop, making the wheel curtain vents slightly larger, to optimize wheel tire changes to meet/exceed OEM performance?

im not so anxious to spend thousands to look even cooler with high end rims, making more of a theft target for theft, if we may or may not be making true proven performance gains?

Honestly, I only know enough to be concerned here, not the specifics but am sure aerodynamics and Honda’s somewhat unusual combo of vents, spoilers, wheel well bulges, and ground effects (very smooth aero belly) were no accident and together with clever steering geometry changes were able to do so well in track performance.

in theory, if you could add one more inch in overall tire diameter, you could achieve higher top speed, perhaps offset by the higher rotation weight.

8) Conversely, for those using 18” say 30 or 35 series tires, are they not reaching same top speed? Are they able to accelerate/and stop faster with perhaps less overall wheel weight?
The answer I’ve seen based on feel and the equivalent to Butt dynos is yes, my expensive lighter rims are better and spin up/down faster. What other areas suffer or benefit?

9) lighter tires & rims besides any impact from aerodynamics also behave differently if the result is less suspension mass. Recognize the lighter shells will be moved up and down more by imperfections so in purest form, could spend less time with good traction.

Think of all the specific systems and subsystems that are possibly impacted by shell/tire changes.
I see this as an Apple-Android situation. Honda optimized all aspects (or some might say compromised being multi-purpose vs performance/racing oriented) using their known, specially created Conti’s and OEM rims much like how Apple controls their operating environment, same, known, you get the idea.

10) Although there are great charts and some smart advice to choose what works with rim/tire combos, these seem to. Based on what looks best (frankly boring looking flat mulitspoke) vs where’s the data comparing all sorts of variables performance aspects, to include drag, for the same vehicle changing nothing but rims& tires?

Finally, Are we sheeple because with all the great design Honda did for us regarding wheels/tires we feel the need to armchair q’back it in a well meaning effort to improve upon years of engineering considerations using a tire ‘this fits’ chart?

I know what I know and what I don’t know.

I know I’ve learned to trust experts more than just doing what looks nice if it doesn’t do anything but spend huge sums?

B/L is do the R wheels/tires need changing (other than summer/winter climate locations) or do we just do it to be cool? I’m good with either. I certainly have made lots of cosmetic changes to my R that have no performance benefit but am making a huge effort to say we’re missing so many aspects that we think help/not/mixed bag other than feel good. The +5hp sticker comes to mind and the my red coil overs are better than your blue ones.

If you made it this far, I understand you might be too exhausted, mad, or confused to answer, that’s fine. Broaden horizons, best way is gain altitude.
 

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I’m curious I just ordered a set of 18x9.5in et44 wheels. I already recieved a set of 265/35r18 tires as I was told they fit zero issue. However it is an overall small circumference. Very minimal. A 255/40 would be the same circumference and not effect the speed. A thicker sidewall. I prefer the thicker sidewall because I feel it may offer a smoother ride. Any Input? Would a 255/40 work with out rubbing?
 

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I’m curious I just ordered a set of 18x9.5in et44 wheels. I already recieved a set of 265/35r18 tires as I was told they fit zero issue. However it is an overall small circumference. Very minimal. A 255/40 would be the same circumference and not effect the speed. A thicker sidewall. I prefer the thicker sidewall because I feel it may offer a smoother ride. Any Input? Would a 255/40 work with out rubbing?
based on your offset, I'd say you wouldn't have any rubbing when lowered...definitely not if you're on factory suspension.
 

AdamD19DFK8

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I've been on 265/35/18 +45 since the first week of October and I absolutely love them. Handles better, stops quicker, accelerates faster, looks much better. Over 40 pounds of unsprung weight reduction. They do kind of poke slightly in spots down at the bottom,but otherwise look very flush. Id def recommend rally armor mud flaps for them as even the stock wheels throw a ton of dirt/water down the side of the car. Plus they help compliment the wide look of the car. The sidewall is plenty, especially compared to a 245/30, though I believe 265/40 may be too much. Speed difference is minimal, they come out to a 25.3" diameter. I just put a -1.8% (forget exact value) into the speed correction in hondata. The speedo matches up with the GPS speed on my radar detector so it's good enough.
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