My 2 cents:

I drive an 81, because I like the looks. Whenever we have a tour here, no one looks at the ZR-1 or the Callaway, they look at the c3's. C-5 and C6 and even c7's are all over so. cal. I also find even though it is pushing 40 years old, it holds it own on the road. Straight line racing is where I lose. (200HP)

That being said, I have 15" on mine because they are cheap, and look correct.

I have been in an 81 with a LS conversion that has 18" wheels and nittos.
It will corner well enough my butt takes a bite out of the seat. No way I could corner that fast with 15" tires. It would spin out.

You can't have it both ways. Choose for looks, or choose for performance.

 

 

I agree with what you stated above.

I currently have poly bushings on front sway bar, all Moog front steering parts, Moog coil springs, VBP composite spring on back end, Bilstein HD shocks all around, factory stock rear sway bar, front spreader bar, heim joint rear strut rods, and adjustable steering tie rods. If I was starting over, I may have went poly bushings on the A Arms and elsewhere that may make it better.

I know I could take further steps on the suspension, but I am well along the way. I keep flurting with 17 inch Torq Thust wheels and whatever 27 inch tall performance tires are out there.

What I would lose is raised white letters on the tires, which I love. And I would lose my classic factory aluminum mag wheels, which look so good on the car. I have seen some Vettes on this forum with 17 inch Torq Thrust wheel and tire combos that I do like. I really wish I could try it out before making a big change. I have been working on cars and motorcycles a long time, and I have been swayed to make "improvements" many times that turn out to be far less of an improvement than advertised.....and sometimes it takes something away. If I did it, it better be a very noticeable improvement.

I restored a 73 Harley Electraglide...upgraded to all the best stuff available. When all was said and done I turned it into almost a new Harley...but, in reality its design features prevented it from ever performing like a new one, and the worst part is the character loss. I would go to bike shows and see an original 73, even if it was restored to original, and I would fall in love with it. Then look at my super duper upgraded 73 Shovelhead, and all the coolness of it was modified right out of it. I sold it for a loss.

I have been very careful to NOT do that on my 77 Vette. And so I worry about that in making this change. My total body off restoration on my car was guided by my previous bad experience with the Harley. The guiding principle was.....build it to be reliable, improve things that matter and are going to make the car fun....but be careful to not lose the "character" of what attracted me to the car as a 16 year who dreamed of someday owning one. I have achieved that.

My engine is modded up with all the good stuff, but it still looks like a Chevy 350 when you open the hood. All steel parts powdercoated the correct black sheen of original paint.....better but looks the same. Exterior and interior all look very original, but built to last. In every area, I held to original appearance and design as much as possible. Changes I did make were because if a 77 Corvette original car was going to provide me a very poorly performing sports car, I was willing to change.....so that's why I have a 375-400 HP motor, a tight manual steering system, and all the aforementioned suspension upgrades. I won't upgrade to a 5 speed manual because I don't want to lose the cool character and crudeness of the Borg Super T-10 four speed. Engineering the classic nature of the car, and accepting and embracing certain less high tech stuff is important to me. Otherwise, I could have just bought a C6 or C7. Its a fine line that I strive to be careful to not cross.

With that being said, I do like the fun of the twisties, and an upgrade to a classic looking Torq Thrust wheel is something that could be in my future....maybe. Those wheels do represent a classic look that existed in the 70's. What I would never consider is mounting later model wheels, or custom wheels, to my car......JB78-L82 has C4 wheels on his car, and it just ruins the look...in my opinion. He makes that compromise as he has stated to have performance of modern tires....I will not. Certainly any modern wheel design has no place on my car. The 17" tires are not nearly as obviously larger than the 15 inch, as long as the total tire diameter is 27 inch minimum, and with classic look of Torq Thrust or Cragar 5 spokes, would be acceptable......time will tell.

 

I have a very similar suspension set-up as you both, and when I got it all together I had an old set of 255/60r15 Goodyear Eagle GT IIs on stock 76-82 Alloy wheels (I am all about low weight stuff). When I took a ride after I got the car all together on my 400whp LS/T56 swap with 3.73 gears; the tires would slip and slide like I was driving on ice under any type of pushing. I could have gone with some fresh tires in the same size, but I figured I needed some good performance street tires which I only found with bigger wheels; So I switched to 245/50r16 up front, with 255/50r17 (same relative size as stock) Nitto Invo UHP tires in the rear on TT2 to try and keep some classic look. There was a huge increase in traction, but a slight decrease in comfort. I didn’t notice anything as far as tire bouncing or flexing, but I also have about 500-600 lbs in weight reductions that greatly helps with handling and tire stress.

Now that my tires are about 4 years old (about 5k miles) and half wore down due to still not enough traction, I need to find better tires that won’t add much (if any) extra rotating mass/resistance, and decrease ride comfort like the 18s I tried did. I also really like the classic looking combo which is why I am leaning towards the Mickey Thompson 15 inch street drag radials.

 

15 inch also has less rotating mass/resistance, and better ride comfort in general (comparing apples to apples). If you make suspension changes to improve ride comfort, a 15 inch/taller sidewall tire is still going to ride smoother than 17/18s.

Plus, the look is not about “a desire to stay completely stock” with having a 15 inch wheel/tire combo (that’s for the NCRS guys who pay for original skinnies). The people on this thread all have mods in some way (this is a mod thread). Some of us just prefer the more classic look to fit our classic bodies better, but still have some modern mods hidden underneath (including updated performance 15 inch tire options).

Yes, bigger wheels/tires have more options in the performance arena, and might always handle better, but there is more than just one trade off to consider.

 

I have found some 17" and 18" combos that are lighter than my stock 15", so I don't necessarily agree with that statement.

 

Can you substantiate this in any way with actual numbers? Rotating mass is defined as the moment of inertia and is the resistance to torque. The moment of inertia is essentially M X R-squared with the mass at the perimeter being the bigger (i.e. R-squared) factor. Tires of the same diameter are going to have pretty much the same amount of rubber at the periphery where R-squared is largest. The density of rubber is upwards of 0.9 ounces per cubic inch, whereas, on a quick search aluminum is 1.5 ounces per cubic inch i.e. heavier but not by much . Steel however is some 5 ounces/cubic inch which I'm guessing all 15" rally wheels are made of and that is a lot heavier

 

That wives tale is mentioned over and over again and probably way back in this thread, someone else brought the heavier weight issue of the combo 17/18 and ultra high performance tires/rims and I too stated that I weighted my 17's versus the OEM 15 inch rim combo and the 17's were lighter. Facts do not seem to matter for some....

 

We have gone over this so many times already in this thread, but here we go again for the new people;

I never said the stock 15 inch steel wheels were lighter weight (25 lbs) than plus sized combos.

If you compare apples to apples; 15x8 inch Torq Thrust 2 (16.6 lbs) to a 17x8 Torq Thrust 2 (18.5 Lbs) which I have both personally weighed, there is a difference. But then if you add 18x9 (20.6 lbs) or 18x10 (21.5 lbs) TT2 which I have also weighed, you are adding even more weight. Plus you are moving weight more towards the outside of the wheel/tire assembly each wheel size you go up, which adds more rotating resistance (Tires weigh about the same with either wheel size).

There is no need to input mathematical equations that fly straight over most peoples heads; it is common sense to anyone who knows a bit about cars and rotating mass, such as weighted flywheels, etc. that when you move weight out from the center of a rotating object, it becomes harder to initially rotate and then stop from rotating.

This is a big reason why (other than the tire height change) Trucks lose acceleration and braking performance when they put big wheels/tires on. They may drop lower gears in to help get the acceleration back, but the truck will still be harder to stop with the bigger wheels/tires taking more energy both ways.

The changes we are making in our wheel/tire combos might be small in most cases, but they still make a difference which should be considered. With looks set aside (because everyone will never agree on what looks best), you will in fact sacrifice at least some HP/acceleration and MPG (efficiency) for better handling and traction in most cases, with bigger wheels.

So do you want/need the extra handling and grip that plus sized wheels usually dominate at (and a new look), or do you want the classic look and better efficiency that 15 inch offers?

I desperately want to get great performance in classic looks, but I am pretty sure I will have to find a medium making sacrifices on both sides of the spectrum. This is probably the hardest choice we have to make as classic car owners who actually drive them.

 

I don't LOVE them but I had to make a sacrifice of looks versus performance............

 

Yeah, that reminds me of when I put 2005 16 inch Mustang wheels on a 1966 Mustang I restomoded. I didn't love the looks and got a lot of mixed opinions, but they were definitely lighter and performed better than the stock 14 inch steelies.




So Sorry, I promise to never post a picture of Mustang again!! Don't beat me up guys, LOL

 

Mine are SLP C3 specific wheels that are no longer made (quite a few folks on the forum have them which helped convince me that I could live with them)....pretty much look like the C4 ZR1 rims......at least they LOOK like they came from a Corvette...just not a C3

 

Thank you....

 

JB, please don't take offense. People's opinions on looks is same a taste of food....there is no right or wrong. Its purely a personal thing. I had no intention on bashing your choice, as I know you have stated in other threads that you have chosen performance over appearance.

The picture does reveal the other aspect of larger wheels that I would have to find a way over is how much they often do NOT fill the wheel well enough. It is very obvious, and some are worse than others. Quite often they look like mini-wheels not properly matched with the openings. That is why I have said I would have to make sure the tire I used would be at least 27 inch in diameter, and slight more would even help. The tire outside diameter should be concentric with the wheel opening in size and location to look right. I think the outside diameter of larger wheel tires is almost more significant to me in the look and stance than the small size of the tire sidewall profile.

 

Yup, bigger wheels with smaller sidewalls make the wheel well gap stand out more, even if the 2 different combos are the same height. Its kind of an optical illusion that stands out in a bad way to me too.

Some views/pictures make my car wheel/tire size and fender gaps look good (with the right angle and lighting), but I often look at my car in real life and I say to myself; I need bigger tires to fill those ugly gaps like the 15 wheel/tire combo seemed to do.

If you lower a car with bigger wheels it still doesn't look quite right, and it takes away ground clearance and suspension travel for nasty street roads and speed bumps. I HATE crawling over speed bumps, and still scraping my exhaust.

 

No offense taken

That was an older picture before the rebuilt 355 L-82 was completed with aluminum heads now and the corrected stance is this:




Cut front coils by 1/2 coil.......

 

That looks much better, especially at this picture angle. I delete all the pictures that are taken at bad angles and make my car look funky, but I cant do that in real life.

 

Both front wheels/rims fill the wheel wells completely now......

 

do you have a picture straight from the side?

 

Not with the newer stance with the cut front coils...sorry