unoracer
New member
I am currently looking at fitting 15" wheels to my race car, in an effort to create a bigger footprint of rubber on the track, but have to admit, I don't fully understand offset measurements. Am I right to think it is a measurement of where the 'hub' of the wheel is in relation to the most inner and most outer part of the rim? I am not sure what the standard offset is for an uno turbo rim, but I currently have some fiat 5.5x13 magnesium alloys with an offset of 38 I believe, which requires spacers to be fitted to clear the turbo calipers. I want to get an idea of the offset I need for 15" rims, as I don't want to have to use spacers, as the extra width (prov 7x15) is likely to use all of the room under the arches as it is!! My racing regs allow me to bend the arch lips out of the way, and I am also allowed to use the turbo spats to help keep wheels under the arches, and I'm worried I will get clearance problems if not careful! I have already had problems fitting lancia 6x14 rims with slicks catching the rear arches, although the lips were not 'bent' out the way at the time. Any advice would be appreciated. I am running 3.7 final drive, which I intend to change to possibly to 4.5 - 4.8 to counter larger rolling radius of larger rims/tyres etc. (I will of course work this out properly on a gear calculator, but have been told I need circa 4.1 final drive if I stay on 13" rims with 180/60 13 slicks
