SVTF R-Compound Tire Size?

[leierb]

I am going to be autoxing my SVTF in GS this year, but need to purchase a fresh set of R-Compounds for it. I was looking at the Hoosier and Kumho tire specs and noticed that the Kumho 235/40WR17 Ecsta V700 is not only wider, but lighter and smaller in diameter than the 225/45WR17. In autoxing, this is a triple win situation! Does anybody know if this will cause any mounting problems on the stock rim, or any clearance problems in the wheel wells or front struts?

By the way, here’s some advice for anyone who is going to mod their SVTF for any other class than GS. Getting power down is already a huge problem with SVTF, so if you are thinking of increasing engine HP, you really should consider investing in a LSD, like a Quaife. A couple of my former competitors did this to their Mini Cooper S’s (same tranny as the SVTF) and it completely changed the car.

Thanks

#68 of 4788

[jstevens1]

I'll agree wholeheartedly that this car NEEDS a LSD. However, that mod alone puts you in either Prepared or Street Modified category in SCCA Solo II. That's a BIG jump from Stock. Honestly, I'd advise anyone to go one category at a time. Do the tires, exhaust, and other little stuff in stock first. When you change your shocks, do the whole suspension and dive into STS. Trust me, a front upper strut tower bar is plenty of help in a Focus. STS also allows a few other good engine bolt-on's. But the jump STRAIGHT to an LSD, and therefore Prepared category, leaves you WAY behind your competition with a lot of catching-up to do. While you're in there for the LSD, you may as well swap to a heftier clutch and lighter flywheel.

But that's just me, and I could be wrong...

Take care...

[LMarx]

I think you would have some clearance problems. Do some measurements. Past some paper over the tire to see the change. I would think that a 235 tire would need a wider rim than 7 inches. If a rim is too narrow, the tire wants to roll over rather than work.???????

I'm running G Stock and using the Kumho Ecsta 225 45 17. Havn't received them yet, but called the order in today!!!!!!!. They are 96.75 minus101.25=4.5mm taller. That is .177165 inches more times two for diameter change.

that means that the car is raised .177165 inch, and the diameter of the wheeltire is 2x .177165=.35 inches. I don't think that is significant. it is about 11/32 inch. 5/16 or less than 1/4 inch. So the car is raised less than 1/8 inch. Since the car is easy to launch with wheel spin, I don't look for it to effect the start of an event.

Ask the folks at Tire rack for some numbers. Be aware of any wheel offset change will compound the effect of a larger tire.

[LMarx]

My 225 45 17 Kuhmo's fit fine yesterday at their first event. I have a 45 mm offset wheel.
Never thought to go 205 40 17 which I saw on a track Audi at yesterdays Solo II. They were REALLY low profile. I think they may be a better deal as they lower the gear ratio with less than stock diameter. That may be the size I go with upon replacement of these new tires.

[LMarx]

I saw 205 40 17 on an Audi at the last Solo.
I think I will go that direction next time, rather than 225 45. the 40series gives lower car, lower gear ratio, and shorter sidewall for quicker response. And, the tire fits the 7 inch wheel width better than the 225. 225 really wants more than 7 inch width for optimum performance.
All positives for a tire used for competition.

[leierb]

I went ahead and tried the 235's and they fit (sort of), but there are some issues. First, they do scuff the driver's side inner wheel well in hard bents and very high air pressures are needed to prevent them from rolling over onto the sidewalls.

They work well though, 3rd and a 1st in my first two events, and I think I am only driving around 80-90% of the car's potential. The true test will be a SCCA ProSolo later this month.

That brings me to this question!

Has anyone tried installing the Koni Sport shocks in their SVTF???
How do they perform???

:wtf:

#68