PatternDayTrader

Looks like that drivers side front tire is almost off the ground .. so I guess if your wheels didn't fit right then you would know about it. Lol .. What speed are you going when that pic was taken ?

MatthewMiller

That was actually the previous owner (MSR on these forums), I believe at Motorsport Ranch just south of Houston, but I don't know what turn. So I guess the correct answer is "pretty fast." I didn't have a good recent pic at an angle that shows tire poke for the purposes of this thread, so I just posted that old pic.

PatternDayTrader

Yeah those wheels barely fit, but it looks like they fit. I like the wider wheels. Looks like they might be helping in that corner too.

barchetta1

Thanks guys.. no word back yet.. hopefully I didnt send him muttering something shaking his head..

Im misunderstanding backspace then. Im using the following to determine bs... he measured to the very outer edge with a straigh edge.. this drawing shows BS to be to the bead face.

https://www.wheel-size.com/calc/?whe...cl=30mm&sr=0mm

Hopefully he is out and will accommodate when he returns.. If I had just gone a little slower I woudnt have put everyone through all of this.

WVZR-1

Forget the Internet calculators 'unless/until' you understand the math. There's many sets of wheels stacked in the corner of shops where the buyer 'DIDN'T GET IT'.

barchetta1

I glad you hung in there with me... damnit wish he'd respond. I got your PM, thanks...

MatthewMiller

I don't think that page intended it to depict it that way, but it's not a very clear pic. But in any case, that's not the correct way to measure backspacing. The correct way is to lay a straight edge across the inside edge of the wheel and measure down to the hub face.

barchetta1

He isn't responding. I'm 99% sure it's what he measured then. So 7.5 and 8.5 respectively.

barchetta1

This fit on a C5 with no tissue does that mean anything?

MatthewMiller

You'd have to look up offsets on a C5 to compare them. I know a C5 generally uses more offset than even a later C4.

But anyway, don't overthink this. The fronts will fit perfectly and the rears may or may not need a 1/2" spacer. It's that simple.

barchetta1

[QUOTE=MatthewMiller;1596803263]You'd have to look up offsets on a C5 to compare them. I know a C5 generally uses more offset than even a later C4.

But anyway, don't overthink this. The fronts will fit perfectly and the rears may or may not need a 1/2" spacer. It's that simple.[/QUOT

barchetta1

[QUOTE=MatthewMiller;1596803263]You'd have to look up offsets on a C5 to compare them. I know a C5 generally uses more offset than even a later C4.

But anyway, don't overthink this. The fronts will fit perfectly and the rears may or may not need a 1/2" spacer. It's that simple.[/QUOT

Trying to work out a deal with shipping.. I think I irritated him with all my requests especially after he agreed to ship.. will let you guys know..

And thank you all again for all of this information and especially your patience.

barchetta1

Well, it looks like my photo request pushed him over the edge.. ah well, will be others.. just these were priced really well.

WVZR-1

A very good learning experience.

You should have a good understanding of 'the math' - learn the math so you can accomplish a much better conversation the next time. Don't rely upon charts etc until you understand the math.

Where were the wheels? I ain't interested but maybe someone local to the guy would put an eye on them for you or maybe 'broker' the buy.

It's entirely possible that you ran upon someone that actually didn't understand. A seller will generally have much better success with a sale if he references 'offset' and lets a buyer determine fit.

Back-spacing only works where you've a tire/wheel combination to fit a specific wheel-well. Then it's all important!!

Master the formula for calculating back-spacing from offset and you can double check anything a seller mentions in a for sale ad.

Backspace = (Rim's Tire Width + 1)/2 + (Offset/25.4)

oilyfishhead

My 2 cents worth:

Check the availability of big (285-295-315) 17" street tires. You'll find there's not much to choose from. I had to go to a 18x9.5 rear to find a decent selection of tires.

Later C4s (my '94) use the same offset as the C5s.

barchetta1

I found at least 3 major brands were available and just went through the process. I dont care at all for an 18" on the c4. The height of the car is just not right in my opinion. I wish that didnt bother me because many more options exist in 18" as far as wheels. I guess the 18" rear only is least objectionable to me... but Id rather stick with 17s as long as possible. Nitto, continental, and one of the "B" brands carry them. Name is eluding me.

I really like the continentals I just bought.. really quiet and a great ride.

I still have a foot in the door with the seller, if it doesnt pan out I may post the info for a local purchase.

MatthewMiller

That is not true at all. A 17x9.5 later-C4 rear wheel has an offset of 56mm. I C5 rear 18x9.5 has 65mm offset. They can be used on a C4, but may need spacers to fit, and even if they fit without spacers they will sit noticeably inward of the OE C4 wheels and won't look quite right.

oilyfishhead

This is incorrect then?

https://www.zip-corvette.com/97-04-0...-5-18x9-5.html

These are what I bought for my '94

MatthewMiller

Those are not OE wheels for any Corvette. They are reproduction C6 (not C5) "ZR1-styled" wheels in a size that didn't come on real ZR1s. The 2009 ZR1 had 19x10s and 20x12 wheels. While the wheels you bought will fit a C4 just fine, they have nothing to do with any real OE C5 wheels.

oilyfishhead

OE has nothing to do with it. We're talking offsets here. Late C4 and C5 offsets are the same. 56mm (front) and 57mm (rear) not 65mm.

OE C5 wheels fit perfectly on a late C4.