Advise Req: 18x9.5 or 18x8 Wheels on '75

[WayneLBurnham]

Hey all

I know this has been covered a billion times (not even sure if it shouldn't be on C3 Reg. Forum):

I finally re-engine my puppy this weekend and have the funds now to finish this project to a good medium stage - so, with the new OD and motor, I need better tires and the wheels to mount them on to use the speed she's capable of (not to mention improve handling even more.)

I am getting a set of Centerline's numbers, like their "Mojave" style of their "Billet" series or their "Dagger" style of their "Sundance" series. They are reasonably cheap, all forged and reasonably light. On all their lines when you order, you specify the offset and they do it a the same cost, so there is no need for spacers.

I know with the 18" change you actually usually get better clearance of everything than the 17", but I need advice on if the 9.5" will fit and what offset to specify. I want the same size all the way around.

I would prefer the 9.5" as there is a little better selection of slightly larger final diameter and tread section tires, particularly in the Michelin Pilot PS2 Y rated, but if they just won't fit regarless of backspacing without putting flares on now, I'll stick with the smaller. (I do plan on flares and even wider meats, but not at this stage.)

One particular 265 offering yields a 26.7" diameter with 10.7" section, but recommends a 9" or even 9.5" rim - whereas the largest recommended 8" rim version is, I believe, 25.3" and 9.7" (that is one of the 245 offerings.)
The 265 is the OEM for some Porsche and, posisbly more importantly, is rated at much greater weight loading than any of their other offerings as well.

Even with this weak *second* *temporary* small block, I have plenty of power (450hp/480tq) and am most concerned to increase top speed and lower engine speed (as well as increasing tread contact.)

Mine is highly modified, with complete VBP suspension on front and rear, conventional sized brakes and rotors (although aftermarket), and, for that matter, both nose and tail are '82 style, but the rest of the body is '75.

I drive this thing a lot (not lately! ), super hard, super fast and on all types of roads. The first three years she was running I put on about 95,000 miles. The thing already shows a lateral handling of 0.67g's, with mushy 15" Pilot V's on 15" heavy steel rallyes.

I would like to order these by end of next week or the beginning of the following at the latest.

I appreciate any insights anyone can give me - especially any real experiences.

 

[80convertible]

You may be able to get away with 9.5" and 265 series tires in the rear without offset trailing arms but I don't think you can get 265 series tires up front. My 255 series tires hit my frame at wheel lock and the later C3s had more clearance in the wheel wells. I just installed 17" C5 wheels and I'm going to run 255 series all the way around on 8.5" wheels.

 

[KANE]

I would prefer the 9.5" as there is a little better selection of slightly larger final diameter and tread section tires, particularly in the Michelin Pilot PS2 Y rated, but if they just won't fit regarless of backspacing without putting flares on now, I'll stick with the smaller. (I do plan on flares and even wider meats, but not at this stage.)

I'd go with the 8" wide wheel. I've never had (or seen others) problems with that width.