Mach V Dan Posted October 24, 2019 Share Posted October 24, 2019 Today I put some 20" wheels on my 2020 Legacy XT Touring. I thought I'd share a little bit about my experiences, how it fit, and some of the calculations I did. If other people want to add to this thread later with more wheel/tire fitment info, that would be great. Intro: At least in the US, the 2020 Legacy comes with either a 17" wheel (7" steelies or 7.5" alloys) with a 225/55R17 tire, or an 18x7.5" wheel with a 225/50R18 tire. Note that the 18" tire is 0.7% taller than the 17" tire. The speedometer/odometer is calibrated to the tire size the car came with. Even the 18" wheel looks very small on this car, and the big plush sidewalls are not very sporty in appearance or in feel. The wheels and tires are also not very flush with the fenders, although that pushed-in look is not as pronounced as with some Subarus. Calculations: I considered several options for larger wheels/tires. I really felt from an aesthetic standpoint a 19" wheel was the smallest I wanted to do. My XT Touring came with the larger 18" tire, so I used that as the baseline diameter for my tire calculations. 225/50R18: 26.9" diameter, 84.3" circumference, 8.9" tread width, 4.4" sidewall. I wanted a wider tire, so I looked at some 245 width options: 245/40R19: 26.7" diameter (0.7% shorter), 83.9" circumference, 9.6" tread width, 3.9" sidewall. 245/35R20: 26.8" diameter (0.4% shorter), 84.0" circumference, 9.6" tread with, 3.4" sidewall. That's a pretty good match right there, and if I was choosing wheels I would just pick a 20x8.5" wheel with a slightly lower offset than stock, and go with that. However, my friends at Titan7 had some 20x9.5" forged wheels I could get for a very reasonable price, and a 245 tire would have been very narrow on that wheel. Time to go back to the calculations. Specific specs on the wheels: Manufacturer is Titan7, style is called T-R10. Color is Satin Titanium. Size is 20x9.5" 5x114.3 +63. They are forged and weigh 22.1 pounds each. Centerbore on these is 68.05; I think they were originally made for a Lotus Evora? I had to order some custom 68-56.1 hubcentric rings from ebay so the wheels would be hubcentric to the car. Back to the tire sizing: 265/30R20: 26.3" diameter (2.2% shorter). The 265 tread width would be a perfect match to the 9.5" wide wheel, but measuring fender and strut clearance, it was looking like a 265 width would be a very tight fit. Plus, I try to keep the diameter within 2% of stock to minimize speedometer/odometer error. 255/35R20: 27.0" diameter (0.4% taller than stock), 84.9" circumference, 10.0" tread width, 3.5" sidewall. Not too bad a fit on the wheel, looks like it'll just barely fit between the front strut and the front fender. I think we have a winner. Plus, that happens to be a fairly common size for high-performance sedans, with lots of options in terms of brand and tire type. I ordered a set of Vredestein Ultrac Vorti tires in that size. Fitment on the car: The rear suspension on the 2020+ Legacy is a variant of the same multi-link setup that Subaru has been using on everything since 2008. One nice thing about it is that there's almost infinite rear inner tire clearance, so my super-high-offset wheels worked fine. I only had to worry about the inside of the tire rubbing on the fender liners and the brake line. Both cleared. Note that the lower suspension arm and the rear knuckle itself are now made of forged aluminum. The front suspension is a strut design like most modern cars, and the shock body is the limiter in terms of how far inboard the wheel/tire can go. My +63 20x9.5" wheel bumped into the strut, so we mounted some Mach V 10mm wheel spacers. The stock wheel studs are not long enough to bolt the wheel on then, so we installed longer wheel studs as well. This effectively positioned the wheel/tire assembly at +53 offset. Pressing the old studs out using an air hammer Note that there is a little access from the back of the front brake backing plate, so you can get the stock studs out and pull the new studs in without having to take the whole front hub apart. Longer stud vs original studs 10mm spacer in place. Mach V Motorsports (my business) makes these spacers. They are unusual because they are Subaru-hubcentric to both the car and the wheel. Test-fitting the front wheel and tire. So far so good -- looks like it fits and everything clears. The back actually has a little extra room at the fender, so the offset back there could be even lower. The front is pretty tight at the fender, and there's very little room between the tire and strut -- maybe 3-4mm? The fenders are pretty much flat/pre-rolled on the inside where the tire would contact, so there's almost nothing to roll. In the back there's just a bead at the top of the wheel well, not even a folded sheet metal lip, so you're not going be rolling that. So there you go. That's about as wide a tire as I think I can fit on this car. If you wanted to make it easier and avoid the front spacers, I'd probably do a 20x8.5" wheel at +48 or so, and a 245/35R20 tire, or a 19x8.5" +48(ish) wheel with a 245/40R19. Dan Mach V FastWRX.com Link to comment Share on other sites More sharing options...
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