I am new here, and pretty new to Corvette ownership. I've got a black 2009 C6 standard coupe (automatic). It currently has summer only tires on it (previous owner lived in Texas), so it's mostly sitting in the garage this winter and I only take it out when temps go over 40F. I'll be getting all weather tires as soon as I can, but I'd also like to get new wheels as well. Its got 245/285 and 18"/19" wheels in the front and back respectively. I'd like to go wider in both the front and back. As I've started searching and reading here on the forum, it seems that there is a lot of things to consider.

Is there a specific ratio of front/rear widths that's ideal? I expect that understeer would be a concern if the fronts are too slim. I don't take it to the track, so understeer isn't a huge concern at normal driving speeds. I'd like to go with 315 in the back, and was thinking 275 or 285 in the front. I'm not even sure if anyone makes all-season tires that size. I also think that I'd need to go with 19"/20", but I've read that that then brings in questions about the ABS, speedometer, and automatic shifting differences due to larger wheel sizes. Are there any good resources that I could read to educate myself on this?

Why? It's my dream car, and I want black wheels with a red lip. I just think that would look amazing.

 

It all depends on what you want from the car if you want to go faster or just looks.

Faster will be lighter and perhaps a 17 inch rear wheel and fronts 18 x 8 but if you want big will be heavier and tires will cost more and IMO not necessarily look better and I can prove that just text me will text some pics of before and after the big wheels.

IMO you can get the looks extra speed and pay less for tires with better tire room and low ride all one shot. David 3054573066

 

if you've done a "search" ALL your questions would have been answered. only about 4 million threads on the subject.

 

I would not mess around too much. And if you do make sure you do your homework, otherwise it might be an expensive mistake.

One thing to consider is the offset when going to new wider rims. Get it right.

One problem I ran into when going with an C6 made aftermarket rim in 10in front and 11in rear 18 and 19 sizes with 265mm front width and 305mm rear width.

Now this was a narrow body car.

The tire on the driver's side rear was flush with the fender when viewed from the rear and the passenger side rear tire stuck out some.

Apparently it is not an uncommon issue, not only with the C6 but Mustangs too.

Has to do with the mating of the frame and body.

BTW I did not like how the car handles with the 265 front and the 305 rear widths.

The steering became more sluggish/heavy.

I went back to oem rims and tire sizes.

 

How you intend to use the car and where you live are two important considerations.
Narrow tires work well for wet areas in the flatlands with straight roads. Wide tires work best for dry hilly areas with lots of curves. Your car came from the factory with wider than normal tires to be able to handle turns better than straight lines. Be aware that any size or compound tire that is different than the OEM tire may require swaybar or spring changes if you intend to push the limits.

If you only drive around town and appearance is the most important concern, any tire will work. Just don't expect any tire to do everything well.

 

I've been doing a lot of reading/searching and it appears that there is *a lot* I do not know. I want 315+ tires/wheels on the rear to put more HP to the pavement, but there are a lot of things that I had never thought about to consider. Wheel fitment, fender fitment, ABS tuning, speedo tuning, etc... I've got a base 2009 C6 coupe, based on what I've read a 315mm wheel width in the rear will require a widebody kit. That is a helluva lot more than I can afford ATM. I don't think wheels/tires that protrude from the chassis is a really bad look, but I don't like the idea of what happens if the shocks compress too far in that scenario...

At this point, I want the looks more than the performance, but over time, that will change. I think what I'll do is try to find the black rims with red lip that I'm looking for with the OEM sizes, and run those while I save up for the widebody conversion to run 275/315 or 275/325. Which in reality would probably be 285/315 or 285/325 so I could just swap the rears for the fronts. This car is a loving work in progress, and I care about the aesthetics first, performance will come later... (as I look at cold air intake systems...)

What is the max width I can run with the standard C6 Coupe model that comes OEM with 245 fronts and 285 rears? I've read anywhere from 10 to 30 mm differential is A-OK, but also that anything more than 20+ will require a wide body conversion. All the black rims with red lip wheels I've seen are Z06 models that come in 275/325 sets... I'm not sure if anyone even makes what I'm looking for...

 

I have a base C6 and I upgraded both my track set and street set of wheels and tires. I would recommend either 18x9 front and 19x10.5 rear or 18x9.5 front and 19x11 rear. Those tire widths still look good on the car with out needing a wide body kit. If you are planning to do some track events TSW Nurburgring are about the lightest weight wheels (roll forged) you can get without going to the expensive full forged wheels. With either of those setups you can easily run a 265/35-18 front and 305/30-19 rear. You can go up to a 315 on the rear but you may not like the look. Anything wider and you would need a widebody for it to look good in my opinion.

 

if it fits, you can use any WIDTH tires front/back. whats important for trac control is the front:back ratio. keep that the same and you will be okay - As far as speed, if you change the height, you will shift the speedo readings.

 

I don't really mind the look of tires sticking out, I guess that makes me the odd one out. What I *do* mind, though, is body and tire damage that could result if the shocks compress too far with tires that are not properly fitted. I've been looking for pics of what a 315 would look like on the rear of what I've got, kinda hard to get the search terms right.

I think I'll probably wind up with 265/305 widths to avoid the potential for damage. Now I just need to find the rims...

 

Just so you understand the physics related to tire widths, it's the shape of the footprint that determines the direction of best traction. Shape is primarily determined by width of the tread, diameter of the tire, air pressure, and weight being carried. The better traction is in the same direction longer dimension of the footprint. Since the tire diameter and car weight are relative constants, the way to change the footprint shape is tread width and air pressure. If you add width and retain pressure the footprint gains size laterally and shrinks forward, so you gain traction for going around corners, but reduce forward traction. It's why Formula 1 cars use short wide tires and 1,000 HP drag cars can run 8's on tall 275's.

 

This really tickles my nerd bone... (what? no nerd smiley?)

I hadn't considered force vectors related to tire contact and how the dimensions of the contact patch would affect the handling for forward and lateral motion. So for acceleration, the biggest concern will be making the contact patch longer fore and aft, while cornering is concerned more with the width of the contact from left to right. The concerns aren't completely orthogonal though since a wider tire will still increase the area of contact, just that the primary benefit of wider tires is better cornering, not acceleration.

 

Nope. The total area of contact remains the same regardless of width, assuming width is the only factor being changed. You can change the surface area by increasing/decreasing air pressure or the weight being supported.

 

Wider does not mean better.
Listen to Hoxxog. People do wide to look cool, not because its the best performing. You can get a 275-295 that will put down all the power you have.

 

Sorry, but this is wrong. Assuming width is the only factor being changed, then the wider the tire, the greater the area of contact with the ground. Area = Length * Width. If the length remains the same but the width increases, the area has to increase. I'm really not trying to be contrarian, but a rectangle that is 285mm in width and (let's say) 10mm in length will have less area than a rectangle that is 335mm wide and 10mm in length. It's the difference between 2850mm^2 and 3350mm^2, clearly the larger the area of contact with the road, the greater impact the tire will have, which means more braking and acceleration power.

 

Doesn't work that way.

More weight, pushes down, making contact patch longer.

http://www.roadandtrack.com/car-cult...-tire-patches/

 

That is what I was assuming was going on, changing the width also changes the length of the contact patch, keeping it relatively static. I get it now, the system isn't simple and is pretty dynamic, as one change will affect several other factors.

 

Just make sure to include the weight of wheels AND tires in your decision. I recently bought a set of Forgestar CF10 in 19" all around (19x10 and 19x12). The rear FS are the same weight as stock. The fronts are about 2-4 pounds heavier. However, the tires I'm going with (Pilot Super Sports) are much lighter than the ones on my car now, so overall I'm saving weight. Plus the ratios will give me the same ratio front to back as stock (325/30/19 and 275/30/19).

 

Actually it is rather simple for the most part. Picture an 8" wide tire with 30 psi pressure on a 4000# car. Now picture the same car with only 5 psi pressure. The footprint just got longer, but not wider. Bump the pressure to 50 psi and the footprint got shorter, but again the width didn't change.
You can do the same thing by adding a bunch of weight and leaving the pressure constant or reducing the weight by simply jacking up the car a bit. Obviously, the footprint width doesn't change until the tire no longer touches the ground, but the length sure gets shorter.

Anytime you change the width, diameter, air pressure, or applied weight, it only affects the static contact patch surface area. It's tire construction, compound, tread, and contact patch shape that affect traction.

 

All depends on what you are doing with the car for lets say road racing have tire dependency as paramount tire been the must important thing it will place your in a category or another some must use a particular max size or won't qualify and often as it is for time attack there is a particular tire you must have to be able to compete.

As for a street and strip as my c6 GS I loved the chrome factory wheels except chrome wasn't my favorite color for the torch red car so I tint em and also had to work on the stance but I got em to look great and for a while I was happy with them.

Then as the only constant is change my wheels priority for that particular car changed, when competing at road Atlanta meet some dudes from BC Forge and they had in display the first ever true deep concave I have ever come across cause to be honest must manufactures tell you "deep concave" but you know in your know er they are leaving a lot to desire in that category.

So armed with that new possibility I contacted BC a few days later and after going true my vision for the new set of wheels they submitted a rendering and it was very close to what I wanted except for the front concave spoke arch was not as arched as I like or could be had so modified the rendering and they got back to me with what was the good final rendering more on that later.

My other must haves are the weight these wheels are eight pounds lighter for the backs and seven pounds lighter for the fronts, next the size went from 19 x 12 rears to 17 x 11.5 tires are seven pounds lighter in the rear now and half the price, new front wheels are 18 x 8.5 tires cost savings of over $200. for the two and six lbs plus did not give up nothing on the way of looks.

Then comes the stance, I like the tire section-with to stick out of the fender but the thread be just inside the fender/quarters panels edge, of course no more spacers so saved like 6 lbs. getting rid of the spacers I used to stance factory wheels.

New wheels offset are + 40mm on the 17 x 11.5 rears and +5 on the new 18 x 8.5 fronts they came out africkingmazing the color transparent black it gives the aluminum a goldish tinsh and of course you can see the aluminum behind the side of the spokes are lighter so is like a natural two tone there's nothing out there to compare to and I sacrificed nothing.

Lots of weight saving, no more need for a dedicated drag pack or transporting and changing wheels at the track, great stance and much less in the way of tire costs so I can use softer compound Hoosier drag radials full time with big bold beautiful white letters and 1/2 price and way more traction street and strip, will post some pics.

 

A lot of good info here. I have a 2009 base C6 that has 19x9 inch front and 20x10.5 inch rear XO Luxury Verona wheels on it. I put 255/35/19 and 295/30/20 tires on it. I would say first and foremost: Boomer has a great point above: a lot of these cars were built where one side in the rear sticks out further than the other. It does not become a problem until you start plus sizing wheels and tires. Some guys on here have claimed to shoehorn a 325 into base C6s, but they had to stick very close to a factory offset wheel. Which brings me to the next thing: pay very close attention to which offset you're buying because it it is aggressive, you won't be able to go far past factory width. My Veronas have a 50 offset front, and 65 rear. The fronts aren't really a problem, but 65 is pushing it for the rear and if I tried to go past a 295, I would have rubbing issues. I have never had traction control issues, but I made sure I stayed very close to the factory Tire heights (also didn't want my speedometer out of whack). You can play with the math, but here is one thing people often do not realize with wheels: when it is advertised as a certain width, that is only the space the tire mounts to. In other words, in reality my 10.5 inch Verona wheel is 11.5 inches wide from the inner face of the wheel to the outer face. It is advertised as a 20 inch wheel, but if you measure the face of it, the outer circle is 21.5 inches. This is to form the lip which goes around the tire, but it takes up space and it matters because wheels are actually larger than folks think they might be because of this. Last point, pay particular attention to the section width of the tire and the tread width because when you are trying to fit with little margin of error, EVERY MM COUNTS. The Pirelli tires I have in the rear had a section width of 11.9. So while I bought an advertised 10.5 wheel, I need to be concerned about the 11.9 inch wide tire that is going on it, and if it is close to the fender, shop tread width as well as it can be the difference in rubbing and not rubbing.