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does anyone know what are the widest tires we can put on our cars. I have 215/45/17 on an Ex coupe. I am looking to get a wider foot print for roadracing, anyone know how wide we can go????

 
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225 is as wide as I would say, but I wouldn't make the tire any taller if you were doing so. It will rub unless you make it shorter, I'd honestly advise a smaller rim size. 15" with 225/50 or something.
Besides that, you don't need to stuff the widest tire you can on there... it'll just slow you down. Find the stickiest one you can get.

 
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what tire are you planing on running....?? because the actual contact patch is different for every model/make. Example. Falken Azenis in 205/50-15 have a usable contact patch that is wider then many tires rated at 225.


and I'm in agreement with Boilermaker on the 15's. I'd be running 13's if there were a good/sticky tire in that size and I could fit them over the calipers.

 
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14" will work on an EX but nothing smaller, I don't know about the other models though, the front rotor may be a little smaller. But like everone else said the smaller wheel will be more effective for acceleration purposes. They will weigh much less.

 
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so the falken's have a wider patch??? also from what i heard the 17's are better for handling where the smaller wheels are better for acceleration. not sure if this is true but the autoxer's around here run like 16 or 17 inch wheels.

 
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They're running 16s and 17s on what kind of cars?
Cuz most people around here with smaller cars are on 14s, mostly 15s, and a few people on 16s. Anyone trying to win something running wheels larger than what came on the car isn't going to have much luck unless they're doing it for tire size selection. But since theres no shortage of 15" tires, theres no reason to upsize.
Personally, I'm getting off my 17s next year and going to 15s.
You get a 15" tire thats race oriented, it'll have a sidewall stiff enough to take the beating. Something like a Falken or Kumho MX.
On an autox course, your acceleration does matter. It does you no good to slug out of a corner because your wheels are big and heavy. Its not like a road course where you have 1000 feet or more between corners... how fast you can get out of one corner and into the next one makes a difference.

 
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easy tip for better acceleration, Braking and Cornering.

1. Get as small of a wheel that will fit over your breaks
2. and as wide a wheel that wont rub the uprights (Shocks)and wont totally destroy the wheel bearings.
3. and as wide and short of a tire as you can get, and as Sticky as you can run legaly in your class.

 
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would it make a differance if the 17's weigh only 15 lbs??

 
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Yeah it still makes a difference. My 17s only weigh 15 lbs. Its a matter of inertia, which I've explained on about 300 occasions, so it shouldn't be too hard do find with a quick search.

 
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heres some info i got when i was researching this subject:

Hey Rabbit,

I believe you are thinking about this with the right perspective. Most people make the mistake of trying to add larger diameter rims thinking that will make their car work better, but more often than not that actually hurts performance.

The one thing you want to be mindful of is ending up with a sidewall that is too short and therefore too stiff to allow the tire to bite into the asphalt. Think of a dragster's rear tires (or a Champ car, or an Indy car, or a F1 car, etc.) - they do not use super short sidewalls because they require some sidewall flex (and the resulting distortion of the contact patch) to get all the power they produce to the ground.

The tires I run on my Civic are 225/45-13 Hoosier A3S03s (DOT radials), and although the aspect ratio (45) is relatively low, the sidewall height is a product of tread width (225) and the aspect ratio. Since the tires are very wide then the sidewall is still reasonable despite the low aspect ratio (basically ~45% of 225 = ~101.25). The result is a large, wide contact patch with enough "crinkle" in the sidewall to get the tires to bite.

The other part of my setup is the wheels - 13" x 9" 3-pc. aluminum rims. They are very lightweight (about 7.5 lbs apiece) which reduces not only unsprung weight (the amount of mass the suspension is trying to manage), but also reduces rotating mass which helps accelleration and braking. The most important characteristic though is the 9" width. I believe your stock rims are 6" wide...maybe 5"...which limits how wide a tire you can put on them before you begin to compromise the geometry of the sidewall relative to the tread surface.

In my case the 9" rims are actually a little bit wider than the tread surface which results in the sidewalls being spread out a little bit (other rim widths frequently used with these tires are 8" and most recently the recommended width is 8.5", although I know of at least on National Champion who runs 225/50-13 Hoosiers on 5" wide rims...its a pretty tight fit).

A rule of thumb is that the lateral stability of the tire is compromised as your rim width shrinks to more than one inch (25.4mm) below your tread width. For instance, an 8" rim is 203.2mm wide...203.2 + 25.4 = 228.6, which is greater than 225mm, the approximate width of a 225/45-13 tire's tread, so this would be a desirable rim width for that tire. On the other hand, a 6" wide rim is is 152.4mm wide...152.3 + 25.4 = 177.7, which indicates that a 175mm wide tire is probably the widest tire you could run on this rim before compromising lateral stability.

So, after all that we have concluded that 185 is just about the widest tire you want on your rims (whew... ).

Now let's think about the sidewall height...on your tires it is ~185 x .7 = 129.5. I could see reducing that a little bit to something around 100 mm...maybe as low as 95 mm. So to figure out what that aspect ratio would be close to you take 95 / 185 = .514...or somewhere between a 50 and a 55 ratio tire. A 50 would give you a sidewall that was approximately 92.5 mm high which is on the border of being too short, while a 55 would give you a 101.75 which is a pretty good height in terms of rip and reduced deflection.

So with a little figuring I would suggest a tire sized 185/55-14 for your car. The question is, does such an animal exist? A quick check of Tirerack.com shows that they sell three very good performance tires in that size: Michelin Pilot SX GT @ $111 (not cheap, but a very good all around tire), Pirelli P7000 @ $66 (great performers and a bargain price), and Kumho Ecsta V700 @ $95 (an R-compound DOT race tire that would provide nearly ultimate grip in the dry and decent grip in the wet, but will wear relatively quickly).

You could also try a slightly taller sidewall in the same width, 185/60-14 and still greatly enhance the performance potential of the tire over the current setup. The Pirelli P7000 is available in this size for the wopping low price of $47 per tire (Wow!). Another tire of interest in that size is the Yokohama AVS Intermediate @ $60 (old school, but tenacious grip for the price).

Another option would be to go with a slightly wider tire (not optimal with your current rims, but would give you the option of upgrading to wider rims in the future to make better use of the tires). Probably anything wider than a 195 on that rim is going to be an issue though, so I did a little checking for 195mm wide tires in 14" sizes and found little if anything below a 55 series tire. So if you were to go with a 195/55-14 series tire then you would have a 107.25mm high sidewall (much shorter than your current tires with plenty capable of delivering excellent bite). There are a slew of excellent tires available in that size ranging from the Dunlop SP Sport 8000 @ $74 to the Hoosier R3S03 @ $138 (though I would strongly recommend against the R3S03 for use on the street).

Just as an FYI - I used to run Yokohama A008RSII's (a DOT competition tire) sized 185/60-13 on a 13x7 rim. They were stretched out pretty far on those rims, but they worked great. The reason I am mentioning this is to point out that you can probably go as wide as a 7" wide rim and still make good use of the 185 wide tires...but if you have thoughts of going to a really wide rim (7.5" or wider) then the 195's will probably be the narrowest tire you could fit on those.

All things being equal, for a daily driver the 185/60-14 P7000 seems to be the bargain. I can't think of a better tire anywhere near that price, and the combination of the tire's design combined with the lower sidewall will really enhance the handling of your Civic. Next choice IMHO would be the Yokohama AVS-i in the same size, followed by the 185/55-14 P7000. These are very reasonably priced tires built with performance in mind, and all of them are available in sizes that will really make the most of your current rims.

I know you basically asked me what time it was and I told you how to build a watch, but I hope that helps.

Good luck.

Brett

 
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now, from another source, I discovered that its not THAT big an issue with lateral stability, that an even wider tire can be used. with that in mind, I put Dunlops on my car of the 195/55ZR14 size.

And I noticed that indeed the car does shake a bit from side to side. When the tread runs out on these tires I'm going back to 185's

 
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thanks for the help guys. so if i get what your saying, i need to get a realy light 15 or 16" wheel with some sticky tires?? also is there any hope of being fast at autox or road racing with a 17 by 7 and some good tires?? (thinking of going with falkens for my next tire. right now i have toyo FZ4s)

 
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Only if you have a lot of HP and Torque..... and even then you'd be that much faster if you had light weight 15's....

Find some nice 15X7.5 wheels and you'll be happy Knowing that Although your car may not look Bling Bling.... its at least race ready.

Function over Form.

 
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one more question what would be better light 16 or 17's or heavier (like 20lbs) 15's cause i could just put good tires on the stock wheels.

 
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You know what would be better? You give someone $150 that you owe for wrecking their rental car.

 
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I have Civic dx 2009, original tire is 195/65R15. Now I'm using front 205/55R16 and rear tires 225/55R16, car look cool and there is space to bounce on unbalanced roads. And it look really cool and i did spraypaintthe rims. Let see if i can upload picture.

 
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7th gen have a very different body...
fitments are different.
You have a 8th gen car.
Ah, last reply on this thread happened before your car was built... Please don't bring back an thread that old for no reason...