Help finding off-the-shelf wheels with +25 offset

[ignaro]

Thanks a ton for the advice. I'll definitely remeasure before buying. I did measure the current wheels with the tires mounted. The tires with sidewall bulge are 9 3/8" wide. The backspacing with bulge is 4 3/8". I'd guess there's 3/8" of tire outside the wheel so the entire wheel is 8.5-9" wide, so a 14x7.5 or 8" wheel. Hard to say. Likewise with the backspacing and offset-- it's around zero.
Kore3 brakes will add another quarter inch on each side. Right now I'm trying to figure out what I think I want-- then I'll find a tire shop that has one of these. The body wheel wells, etc are all odd shapes so it makes it hard to measure accurately from the WMS.



I'm looking at Cray and other Corvette wheels, though even those are $470/wheel. There are some with +37 to +50mm offsets, though they're quite aggressive for a 66 Tempest. I imagine I can get the tire shop to confirm my optimal offset, then I'll run 1/4" spacers or so. That would be fine.
Thanks again.

[TheBandit]

The tires with sidewall bulge are 9 3/8" wide. The backspacing with bulge is 4 3/8".

Backspacing is not usually measured from the tire bulge, but assuming you put a straightedge across the tire sidewall and measured to the wheel mounting surface, I think your current wheels have about negative 5/16" of offset (the wheel is offset outward by 5/16"). The way I calculated this was by taking half of your tire section width (9.375 divided by 2 = 4.6875) and comparing that with the backspacing you measured (4.375 - 4.9875 = -0.3125).

You should measure more carefully to be certain, but let's play with math assuming your current tires have sufficient front side clearance.... the front of your current sidewall is at 9.375-4.375 = 5" from the WMS. You said you want a taller tire, so looking at the Potenza S-04 in a 265/45R18 (diameter 27.4in) it has a section width of 10.5in. If you want the front sidewall of that tire to be the same place as your current tire (5" from the WMS), you would need 10.5/2 - 5" = 0.25in of offset (1/4" or about +6mm). The back side of your current tire is 4.375 from the WMS while this new tire would be 10.5/2+0.25 = 5.5" from the WMS, or about 1-5/8" further inward than your current tire.

[ignaro]

Backspacing is not usually measured from the tire bulge, but assuming you put a straightedge across the tire sidewall and measured to the wheel mounting surface, I think your current wheels have about negative 5/16" of offset (the wheel is offset outward by 5/16"). The way I calculated this was by taking half of your tire section width (9.375 divided by 2 = 4.6875) and comparing that with the backspacing you measured (4.375 - 4.9875 = -0.3125).

You should measure more carefully to be certain, but let's play with math assuming your current tires have sufficient front side clearance.... the front of your current sidewall is at 9.375-4.375 = 5" from the WMS. You said you want a taller tire, so looking at the Potenza S-04 in a 265/45R18 (diameter 27.4in) it has a section width of 10.5in. If you want the front sidewall of that tire to be the same place as your current tire (5" from the WMS), you would need 10.5/2 - 5" = 0.25in of offset (1/4" or about +6mm). The back side of your current tire is 4.375 from the WMS while this new tire would be 10.5/2+0.25 = 5.5" from the WMS, or about 1-5/8" further inward than your current tire.

Thanks a ton. I'll definitely be re-measuring. I'm out of the country for now or I'd start pulling the wheels off again. It seems strange that I would have a -8mm offset but the wheels look like 20 year old AR Daisy wheels so who knows.

I could absolutely settle for a medium-width tire like a 255 or 265 and buy less expensive wheels but I don't think I'd be as happy with that. Folks here convinced me that I want to keep a square setup so I'd like to fit a 275 or higher.

Although measuring off my tire should be reasonably accurate, I would feel much more confident with one of those adjustable tire-mount tools, especially since I can 'try out' tires before buying them. Thanks again for your help.

[ignaro]

After a weekend of research, the only positive-offset wheels that are 5x4.75 and not custom are C5 and up Corvette wheels. The lowest they go is +37mm which should fit well with spacers. They're also available in 18" 19" and 20" and a variety of widths around 10". I'm currently looking at the gunmetal Cray Astoria in 18 and 19x10'ish with a +37 offset. They're about $500/wheel and seem like a good option. I'm going to photoshop that aggressively modern look onto my car to see whether it is indeed what I want. Regardless of design, this is something that fits the size I'm after and my budget. That's a good development in a world where wheels are regularly twice that.

I'll probably be running Pirelli P Zero Rosso tires in 285/45/19 in back and 285/40/18 in front. Not enough sizes from Pilot Sports or other renown street tires. That's 1" extra of wheel plus 1" extra of tire in the rear. Should give a nice mild staggered look. Careful Photoshop will hopefully give me the answer.
All input is welcome!

[gator68428]

I would also check with Bob at house of wheels. He sells quality reproductions as well as used and new factory wheels.

http://houseofwheelsonline.com/corvette_copies.php

I bought my Speedlines from him (18x10.5" all around). He gets them brand new, made in Italy.

Also check ebay and the Corvette forum. Used wheels being sold all the time.

[67rally]

Here are two ebay options. 18x10 and 18x9.5, 5x4.75", +25mm offset

http://www.ebay.com/itm/18x10-DRIFZ-...t/232378567512 :$680/set


http://www.ebay.com/itm/18x9-5-TOURE...4/232336293906 : $575/set

[ignaro]

ebay options.

Oh man, these are great! thanks!
Just how terrible are these wheels? I'm not looking for high-end performance but I also don't want a wheel to break when I hit a pothole. I'm thinking I'd buy higher-end tires and lower-end wheels to save some money. I'm also not certain enough that I'll like the look of any wheels I get so spending less is very appealing.

Has anyone had experience using these in an aggressive fashion? I'll be driving in a spirited manner, doing just-for-fun autoX. No real racing. Google reviews are good.