So I was in a gambling mood and figured I would see if I could find the largest tire that would fit in the wheel well of my 5 speed manual - Little Red. I do a fair amount of highway driving at 4K rpm and I wanted to lower the rpms as much as possible, the only easy way to do this is to find the largest tire that fits.
I found a 175/80 R14 tire, made by Westlake Tires, on Ebay and ordered up 4 of them. The outer diameter is about 11.4 percent larger than stock and as such they throw the odometer, speedometer, and mpg gauge about 11.4 percent out of whack, so keep that in mind. It is also likely they will throw the traction/stability/abs out of wack as well, so if you do this.....its on you. They also raise the car about an inch and have a large sidewall....which looks awesome.
You might not believe it but the contact patch is actually narrower than the stock tires. How can this be? Well, there is so much sidewall the tire has lots of length to spread out and achieve a 175 measurement (measured at widest point, not at the tread). I didn't believe it either but after measuring 3 times, its true.
My MPG has gone down about 4-5 mpg, not bad considering most non LRR tires seem to do about the same when new.
Also, the freeways near me are concrete with inch-wide parallel rain grooves and the tread on these tires love to wiggle and squirm back and forth trying desperately to follow each and every little groove it can. To me its mildly annoying but not a huge deal.
My rpm is reduced 11% which in 5th gear is noticeable and much appreciated.
Oh and yes they fit....barely. The front right tire would rub just a little where the plastic side skirt entered the rear of the front right wheel well. None of the other tires rub at all. The fit is so tight it comes down to manufacturing tolerances of the plastic trim. I cut out about a square quarter inch of plastic and the rub is gone. There was never any rub anywhere else including the wheel well splash guard.