I'm facing a bit of a dilemma with the tires for my Fiesta. When in H stock, I ran the RE-71 and Rival S. I preferred the feel of the Bridgestones. I purchased lighter wheels in 16 inch diameter and kept running the same tires in 205 or 215. Now that I am in STH, I wanted to get some more width and went with a 225 RE-71. The bad news is that they are a 50-series and simply too large diameter. (25") I have to raise the coil-overs for clearance and they can rub the bodywork under high G-loads.
Option #1 is to keep running 2:15 on the 16 inch wheel. (24" diam) This is straight forward, affordable, and other people in fiestas are much faster on this setup so I know there's no loss in performance if I could drive the car more better.
Option #2 is to purchase 15 inch wheels so I can run a 225 tire without rubbing Iand having the CG lower to the ground. (23" diam) Maybe the extra width and lower ride would help me go a little faster?
Option #3 is to purchase some 9 inch wide wheels in a 15 inch diameter, slap on some slicks and go for it. I see EG Civics and SM Miatas on really fat wheels, maybe I should join the club?
WWGRMD?
Only do option 3 if you really want to inspect the undercarriage by rolling it.
fanfoy
SuperDork
5/29/20 1:15 p.m.
KyAllroad beat me to the punch. Do not over-tire a Fiesta in autox. You WILL end up on your roof.
To answer your question: option 1 until you can match the speed of those faster people.
There is a 245 section 15" Rival that I ran on the front of my Mini for years. It was the only 200TW tire wide enough for a 9" front wheel without a stretch. The only real negative was the smaller diameter lowered my 2nd gear top speed. I ran 205s or 225s in the rear and used the difference in front/rear grip for oversteer instead of relying on lifting a tire with a big sway bar.
Are your lower spring mounts for your front coilovers above the height of the tire? That was the difference between an 8" wheel and a 9" wheel on my car. With the spring out of the way, I only had to add spacers to stop the tire from contacting the strut housing. I don't know much about Fiestas but I have heard that wider tires require a bunch of work that may not be ST legal.
This doesn't exactly answer your question, but might be useful or interesting to you and your ponderings.
https://www.turnology.com/tech-stories/yokohama-advan-a052-test-which-is-better-fatter-or-skinnier/
I think typing the question cemented the answer in my head. Incremental width increases are not going to make a difference to someone at my level. I do think that lowering the car will allow me to make better use of the coil overs and the FiST could use all the CG lowering it can get.
I re-read the GRM article on Falken 660s, and placed an order for (4) 205/40-16. 205 and 215 have the same section width, but the 205 is down to almost 22" diam. That lowers the car 3" on tire alone, plus I can drop the suspension too. They are a great price and I had good luck with Falken in the past. Whatever minor differences there are in performance will be lost on me anyway LOL.
