C4 Frame Project

[chevynut]

They minimally meet the requirements using CN's wheel calculators.

ie. 225-45/17 on the 17x8 wheels in front (19 mm OS) and
255-40/17 on the 17x9 wheels in back (45 mm OS)...

I guess I don't see how you figure the 19mm offset wheels will work in front. The front mounting surfaces are 62" wide so the outside of 225 tires would be at 69.35". I think that's too wide and they will rub, imo. You need something closer to 36mm offset or more.

[BamaNomad]

CN: You are right... It was probably *wishful thinking* on my part..

The calculator gives a warning that the tires might hit on turns...

If I use the 9" wide wheels on front (45 mm OS), the warning goes away, but I'd also have to go to 235-45-17 tires to use the 9" wide wheels... What do you think about using the 17x9 +45 wheels all the way around with different size tires on the front and rear??

[Custer55]

CN: You are right... It was probably *wishful thinking* on my part..

The calculator gives a warning that the tires might hit on turns...

If I use the 9" wide wheels on front (45 mm OS), the warning goes away, but I'd also have to go to 235-45-17 tires to use the 9" wide wheels... What do you think about using the 17x9 +45 wheels all the way around with different size tires on the front and rear??

As long as the rim width is within the range for the tire you are using it should be fine. That is what I did with mine. 275's are the recommended tire size for 9 1/2" rims, and I went with 285's on the back and 255's in the front. The rims you are looking at look nice on the 57 Nomad picture you posted.
Brian

[chevynut]

Like I said before, I personally think the tire section width should be slightly wider than the wheel width or it starts to look weird. Sure, you can mount them but who wants the wheel sticking out past the tire (unless you're going to "jump" the car...lol)? Maybe you can't see the width difference until it's more severe, like a 225 on a 10.5" wheel.

A 9.5" wide wheel is actually 10.5" outside the lips. To me, that requires at least a 265 tire regardless of what will "fit" on it. A 275 is a good fit but it's also barely wider than the wheel. Maybe you couldn't see the difference with your eyes, only with a tape measure . I have 295s (12") on 10.5" wheels in the rear.

So even though a 235 will technically "fit" on a 9" wheel, I think a 245 is a better fit. It depends on whether the wheel being wider than the tire bothers you or not. A 235 is nominally 9.25' wide so that's 3/4" narrower than the wheel. I don't know where it starts to become visible.

I believe Newman used to recommend a 245 tires on 9.5" wheels, making the tire almost 1" narrower than the wheel and they "worked". My 245s are just barely under 10" wide and they're on an 8.5" wheel. If I go custom wheels in front they will likely be 8" if I stick with a 245.

If I'm not mistaken the calculator "warning" is set at 67.5" which is what I typically recommend with a dropped car and a stock suspension/steering. I don't think I'm being too conservative because I've looked at a lot of scenarios where tires DO rub and the 67.5" limit is close on a dropped car with a stock suspension. Keep in mind a stock steering box turns the wheels further than a C4 steering rack, and the SAI is different. I measured my Nomad recently and my tires are actually right at 68" outside (they're wider than a nominal 245) and they still don't rub using my late C4 suspension that has not been aligned. But I know I couldn't go much wider or they would, at least at full lock while the suspension is fully compressed (which CAN happen).

So this all depends on the look you want, how low the front of your car is, what year it is, and how much risk of rubbing you want to take (I want zero). If you never turn into a bump at full lock, you can get away with a larger overall tire width. Brian has demonstrated that a 275 tire on a 56mm offset wheel works on his car but it's a 55 (taller fender opening than a 56 or 57) and he may not have hit the worst-case condition while driving it. That's about a 68.6" overall width.

[chevynut]

It kind of cracks me up reading on the other site where a guy said the calculator is good for "getting you close", but he did some careful measuring on his car and with the right offset he made a 275 tire fit under the rear of his car. He used a zero offset rear wheel. The calculator is the tool you use AFTER you do some careful measuring, and it would have given him the same result. Math is math, and with the right inputs the calculator gives you the right output.

[Custer55]

Hey Brian, how do your rear halfshafts sit now? Are they level? Car looks great.

I crawled under my car last night and put a torpedo level on the half shafts and they point slightly up to the outside with the 1" longer bolts. There sure isn't much room to get under there though even for me at 165 pounds!!! need a 4 post lift!! That makes sense that if they are slightly down with the stock bolts they would be slightly up with 1" longer bolts.
Brian

[chevynut]

Thanks Brian, that doesn't surprise me. The only way to get the halfshafts pointed down at that ride height would have been to raise the batwing. If I was to do it again I would have narrowed my batwing and put it inside the frame and a little higher than it is. That would have allowed me to lower the rear another inch or so.

[chevynut]

Brian, how do you think your 10" front tires look on a wheel with a 10.5" outside width? Is the width difference noticeable? I've seen some wide wheels with skinny tires and it looks horrendous imo. As the sidewall gets shorter, the width difference is more important.

I personally think these tires are too narrow for the wheels....at least it looks that way in this pic, aside from the offset being wrong, imo.

[Custer55]

Thanks Brian, that doesn't surprise me. The only way to get the halfshafts pointed down at that ride height would have been to raise the batwing. If I was to do it again I would have narrowed my batwing and put it inside the frame and a little higher than it is. That would have allowed me to lower the rear another inch or so.

Yep, I considered notching the frame a bit to get the batwing up more when I set mine up. I had to cut the floor pan a bit for dog bone mount clearance the way it is so I decided not to do that as it would have required wheel well mods or mini tubs as well to be able to remove the upper dog bone bolt with the body on the frame. Might be a better way to go if you want the car really low in the back though. I think where I ended up is pretty close to how you do yours.
Brian

[Custer55]

Brian, how do you think your 10" front tires look on a wheel with a 10.5" outside width? Is the width difference noticeable? I've seen some wide wheels with skinny tires and it looks horrendous imo. As the sidewall gets shorter, the width difference is more important.

I personally think these tires are too narrow for the wheels....at least it looks that way in this pic, aside from the offset being wrong, imo.

I think they look ok. The section width of the tire is just slightly wider that the wheel. They would be better on an 8 1/2" or 9" wheel. Once custom wheels are in the budget that's what I will most likely go with on the front.