Will these wheels fit my78 gs1000e

[sharpy]

Should be a direct bolt on, assuming you have the proper spacers.

With the 18" x 2.15" rear wheel, the largest tire you should consider is a 120. With the 17" x 2.5" rear mag wheel, you can go up one size to 130.

Please explain ure thinking on two different sizes on a 2.15 rim. We raced a 750 Kat (18") when they came out and a 130 worked great on track and road. Only diff it would be a 130/80 not a 130/90 like on a 17