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How I mounted and balanced the 275/40-17 tires on the front and rear for my 55
After spending countless hours over the last 5 years trying to decide what wheels, and tires to use on my C4 55 I finally made the decision to try and make 275/40-17 tires work on the front and rear of my 55 with the wide C4 suspension. The tire size was picked so I would have several choices for some really sticky tires, which for now is the Nitto NT05 extreme performance summer tire. They have only 70% tread depth new, with a 200 tread wear rating. For the wheels, I wanted something vintage looking, and not modern flat face Corvette wheels with 56mm offsets. Bought the American Racing (china) torque thrusts that were originally made for C4 fitments that are 17 x 9.5 with a 46mm offset with around 7 inches of backspace, plus the wheels were only $145 ea. shipped. So after spending so much time deciding, I spent a little more time on mounting, and using some of the features on my Hunter road force balancer.
First I checked the lateral/radial run-out on the bare wheels. 2 wheels checked out great, and 2 were marginal but passed. I then balanced all 4 wheels using masking tape to hold the weights on so I could see exactly how much imbalance was in the tires. I mounted the tires using my Corghi Master tire machine I've been using for 16 years, which works great. After inflating all of the tires to 30 psi with nitrogen, I checked the road force, and balanced. 2 of the tires that went on the marginal wheels checked out great for road force, but the 2 tires on the really round rims were over the 28 pound limit with one being 44 pounds of road force, which is basically run-out in the tire. I indexed the tires on those 2 wheels, and it knocked the road force numbers by over half. I then balanced them down to the finest level of less than 1/8 of an ounce, the weight of a small rock pebble. Of course all 4 wheels wanted a strip of lead tape weights in between the wheel spokes, so I split the weights in order to hide them out of sight behind the spokes.
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