For starters, to widen 11" wheels that had the proper offset to fit inside the fender, you'd have to add the whole extra inch to the outside. So the backspacing would remain the same but the offset would change a lot. 12" wheels and 335 tires will have to poke out of the fenders a fair amount (1", more or less) to fit on the inside. So you need to budget not only for the tires and widening the rear wheels, but also for real fender flares (not just the GS "flares" that don't add any actual clearance) or an entire ZR1 rear section.

 

A couple things to note: If you pinch a wider tire into to small a rim diameter, angling the side wall, your handling/cornering performance will go down, probably more than the next narrower tire size down, where walls are more verticle.
Second, there are numerous people on this forum that have fit 245 tires and 18x12 rims on rear of C4. But most of them had to do more than just pick the correct best offset for them to fit. Either they add fender flares or they modified their suspensions with shorter custom axle shafts and supports. You then got to ask yourself the possibility of tires rubbing during spirited driving. Are your shocks and springs tough enough to prevent that? There is an excitement factor to want to try to keep going bigger, but there becomes a point where to big just becomes too much of a hassle, unless youre racing seriously and can justify the cost and hassle. For a street car, I'd highly recommend not going over 315s, they are hard enough to fit. Im not saying you cant make a 315/335 combo work, but what are you really gaining?

Regarding to performance.... In the front there are a couple of factors for performance. Water evacuation is one. Another one is, how far away the tire contact surface center point is away from the hub pivot point, and how does that differ from stock. When the pivot point is not in the middle, more of the tire will have drag in turning, meaning needing to break grip to allow tire to turn. And the wider the tire, the more that problem increases. Narrower tires on front can sometimes handle and grip better for that reason. You could probably feel the difference in required steering wheel turning strength, such as when parking. Im gonna argue that to tackle things like grip and water handling, the biggest factor is going to be tire brand, compound and tread, and matching that to your need. Tire size will be more about fitment and cosmetics. Obviously wider rear tires will have more hook, if all things else are equal.

I think the problem people often make is they try to solve everything with one tire and rim selection, which just isn't possible. If you want low cost and local availabilty you can get a federal tire, get decent dry grip, good water evacuation, long lasting, but you'll suffer on wet grip and noisiness, and you probably wont be winning autocross/roadraces. Or get a Nitto 555G2 for a very good compromise of everything, for street/trackday. (my favorite). But again, you're not going to winning races. There are so many other brands that are faster, but more expensive, and shorter lasting tires.

 

Ok, thanks for letting me know that those wouldn’t fit, I wouldn’t want them sticking out or have to pay to get the fenders widened an inch even though I do think that would look good if it was all one piece instead of the stick on gs flares. I think I will just end up getting the 305/35r18 r888r, do you guys think this size would fit and look right?

 

Only way to tell is do it.. Unless someone else has same tires, rims and C4.
I just put the 315's from Nitto on my car, and they are narrower than the BFGs that were on there. All brands are not created equal.
So, buy it and if you like it, which I am sure you will. R888s are on some high end cars running around, as secondary tires after old OEM ones wear out, and have great grip..

 

Please see post #97.

 

I have heard the nittos are all made smaller. I never understood why there’s such a difference between brands because you’re going by a measurement so why would they be any different when they are actually measured. It’s not like millimeters change in size haha.

 

I remember your post but I was just wondering if they would actually fit. I think I would like the look of them and you said they will raise the roll centers but I don’t take turns very hard so that wouldn’t make a difference to me. The only thing I wouldn’t like is the gearing to be lower but the gears in mine are not high already at 3.07 so if they stick really good still on a launch after I change everything I want to on the engine then I could get higher gears like 3.73s.

 

They measure in different areas. Marketing. Sell a 275 from one brand may be the same as a 255 from another manufactuer.
The most famous picture in the car forums is the Good Year Eagle F1 laying next to a set of Summitomos. Both were 315/35/17. The Good Years were much wider. I dont care what anyone says, but manufactures measure from different areas of the tires.
Its like shoes.. Ever had to buy a pair of shoes from Nike that was a different number than one from Puma, or, Vans.... Just throwing names out there.
My OEM Good Years that came on my Vette were much wider than the Firestone SZ50s ( 1997-1999 era). Visually the actual contact patch on the road was narrower, yet they had the same numbers. 255/17 front, and 285/17 year. Looked stupid..
My BFG KDs were visually wider, and wider ( using a ruler) mounted on same rim than the new Nittos I just bought. But same size according to manufacture.
Is it a issue DOT needs to address, Car manufacuers? Who knows. But it is what it is.

 

They will actually fit.

Guys, the issue with nominal section widths vs differing actual sizes is because the section with is measured at the widest part of the sidewall and mounted on a standardized rim at a standardized pressure. Their section widths unmounted, or mounted on your rims, and inflated to different pressures, can vary because of this. To make it more inexact, we know that the industry delineates nominal section widths into 10mm intervals: there is no "317/35/17" tire, for example. So we can assume that the tires aren't made to conform millimeter-perfect to the nominal widths. If the industry measures a new model of tire and it is 311mm, and another new one 319mm, they probably both round to a nominal 315 size. Finally, the correlation between section width and tread width is pretty loose: even tires that have the exact same section width can have very different tread widths.

 

Ok, well that explains why different brands can have such a different looking size when they are numbered the same. You’d think on the lower profile tires it wouldn’t be as hard to measure since the tread is almost always the widest spot since they don’t have enough sidewall to bulge out and then come back to the rim. But between that and the not having an exact size to put down like Matthew said I see what you mean. So a 310 width tire would still be sized the same as a 319 just because they go in ten millimeter increments.

I think I will be happy with the 305/35 r888r’s, I would like the 315/30 too but since I’m going from a 16 inch wheel I think it would be better to get the one with a bit more sidewall so it isn’t as big of a change. Just in case I would think the 315/30 looks like it doesn’t match my car right because I’m used to seeing it with a big sidewall with the 16 inch wheels. I know I will like either size though just because of how wide they are, I think the wide tires just look so much better and fit right on the car. It seems like the 305 in the r888r’s will be more like a 315 since they run pretty wide.

I found out how I can get them with white letters too. At tirestickers.com they do letter size matching so they can make white rubber stickers that will fit right over the letters on the tires. I will send the tires to them and they will install the white letters and then ship them to me. Here’s a picture of how they look only the “R” will be red. I have red stripes to put on the hood of my car so it will match good. Asking as the tires last somewhere around 7,000 miles then I know I will be happy with them, by the time I would drive that much they would need replaced anyway from being old so I don’t think I would need one with better treadware.

 

I think I am ready to order the wheels. I will place the order next week probably. I just wanted to make sure, the 18x10.5 wheels with +30 offset should work then? If the 305/35r18 tires will fit just inside the fenders then I will be happy, if the bulged area of the tires sticks out that is fine as long as the treaded part of the tire is on the inside of the fenders.

 

You have a really good looking car. I think I have seen one just like it but can't remember where.

 

I found a better picture of mine from the front straight on. these are 17x10.5 44offset. the wheels you are looking at will be just like this but with a 1/2" spacer added. add to that the fact that your tires might be a tad wider also. Mine are 285's

 

That’s right I remember the picture you had before. Your wheels do fit good, I’m sure a 1/2” would look about the same. The bulged part of the tire may stick out but probably not the tread. Hopefully that is how it will fit because mine is lowered so I don’t want it to rub the hood when going over a bump.

 

That should be exactly how they fit. The outside edge of these wheels will be in exactly the same place as a 17x11 et36 wheel (a ZR1 spec wheel) on your car. I'm a little nervous about those 26.4" tall tires with this wheel offset. All my experience with wide tires and wheels on a C4 is with tires that are 25.6" tall. If you're sure you want that size tire, then I would probably go for a little more offset, like 32-34mm, just to make sure there's no rubbing on the outside fender liner. If you got the wheels in that offset range and wanted to experiment with pushing them a bit further out, then you could always put in 2-4mm spacers and probably not even have to change the wheels studs.

 

I know I will like that tire size better after looking at pictures of that size. I like the look and width of the 315/30 but for me I would want a bit more sidewall than the 315/30 size. I would get a bit more offset just to be sure but that company lets you pick whatever offset you want up to 30mm. That is the highest offset they will make in the 10.5 wheels. I’m pretty sure the rear will fit and I didn’t lower it as far in the rear but the front should work, if it is a bit too far would it work to have the camber adjusted to bring it just inside the fender without it looking like one of those import cars with tires stuffed in the fenders and scraping the ground?

 

Good question. Yes, you can add a little or lot of negative camber, which means between -0.5 to -2.0 degrees, respectively, for your intended use. In the pics I posted of my car, that was with about -3.0 up front and -2.0 in back. That was specifically intended for autocross and road course performance, and I wouldn't use that much on the street. But even with that much, you can see it doesn't look like those ridiculous "stance" cars! Those are like -30 degrees, and are just stupid.

I don't know if you plan to have the company you're buying the wheels from ship them to you with tires already mounted or not. If not, and you get the tires separately, it might be a good idea to just mount one tire to one wheel and try it on the car front and rear first. Drive it around a couple miles and make sure it fits the way you want and doesn't make any contact. Then if the worst happens and it doesn't fit well, you can return the three unmounted tires (and maybe even the mounted one for at least some credit) and get 295/35/18 instead. That size would be a step narrower and shorter (26.1" diameter) and would have no fitment issues, and it would still have more sidewall than the 315/30/18s you see in my pics. Just a suggestion, since I can't be 100% sure your desired tire size is going fit perfectly.

 

yeah, I can’t stand those high negative camber cars. It doesn’t even make sense because they have such a wide tire but only about 3 inches of it is hitting the ground so the traction has to be horrible. On yours I can’t even tell the wheel is tilted in. They aren’t putting the tires on, I was planning on getting the wheels shipped here and then ordering the tires and sending them to tirestickers for them to make all of the letters on the tires white, they do letter matching. I don’t like it when tires have stickers just placed on the tire but I like the look of white lettered tires. Maybe I will just order one tire like you mentioned though because that would be awful if I spent $1,500 on tires and they rubbed. Thanks for giving all the help you could.

 

I went to the garage where the car is at today and was looking at how far the tires sit inside the fenders. There is quite a bit of room in the inside, I took some pictures showing how much room there is.

 

I was just about to place the order for the wheels but I got to thinking I will just have then send two of them and that way if they don’t fit on the front I could change to 18x9.5 before I pay for all of them. That way I can just make sure they fit before paying for it all.