Does anyone know off hand the offset requirement for a 98 running 17 & 18's?

 

Do you mean the wheel offset...as in backspacing? I am just trying to help. I never heard of tire offset so maybe I might learn something!

 

Wheel offset requirement for front and rear-Bad Heading, sorry
Thanks

 

Depends on the width of the wheels. Diameter means nothing. Offset merely determines how far in or out the wheel will sit relative to the hub.

Not knowing the widths, ballpark offset numbers will be in the 50s for a C5.

 

Here you go (from sticky in C5 General Section):

Wheels
19.2 lbs, front; 21.4 lbs, rear - 97-99 OEM wagon - Src
22 lbs, front; 29 lbs, rear - 97-99 OEM wagon - Src
17 lbs, front; 19.5 lbs rear - 97-00 OEM magnesium - Src
17.5 lbs, front; 19.5 lbs, rear - 97-00 OEM magnesium - Src
18.08 lbs, front; 20.06 rear - 00 OEM standard, thin spoke, high polish - Src
17 lbs, front; 20 lbs, rear - 00 OEM standard, thin spoke, painted, no sensors or centercaps - Src
16 lbs, front; 20 lbs, rear - 01 OEM standard high polish - Src
19.6 lbs, front; 21.4 lbs, rear - 01 Z06 forged - Src
19.2 lbs, front; 21 lbs, rear - 02-04 Z06 cast/spun - Src, Src
24 lbs, 18x10.5 - 00+ repro high polish - Src
28 lbs, front; 32 lbs, rear - Z06 chrome repro - Src
23 lbs, front; 26 lbs, rear - Z06 chrome repro - Src
23.5 lbs, front; 24.5 lbs, rear - Z06 Motorsports, polished - Src
20 lbs, 17x8.5, 58mm offset, front; 23 lbs, 18x9.5, 65mm offset, rear - PWO - Src
22 lbs, 18x10.5, 58mm offset, front - HRE 545 w/clear center - Src
27 lbs, 18x12, 74mm offset, rear - HRE 545 w/clear center - Src
24/25 lbs - Z07 wheel weight, front - Src
28 lbs - Z07 wheel weight, rear - Src

OEM Wheel specs
8.5"x17", front; 9.5"x18", rear --- 97-99 Wagon wheels --- Source
8.5"x17", offset=58mm, front; 9.5"x18", offset=65mm, rear --- 00-04 Thin/Thick 5-spoke wheels --- Source, Source
9.5"x17", front; 10.5"x18", rear --- 01-04 Z06 forged or cast wheels --- Source
17"x11", offset=50mm, rear --- AFS GS --- Source, Source=http://forums.corvetteforum.com/showthread.php?t=448185]Source[/url]

 

Thats Great and Thanks-This is a great group of people!

 

Offset requirements will change with the width of the wheel. A 18x9.5 with a 58mm offset will fit completely different than a 18x10.5 with a 58mm offset.

Many people get offset confused with spacing in front of the hub. Offset changes as a wheel is widened.