Mk8 GTI. I really love the Kumho V730 so sticking with that tire. Limited to 18x7.5 or 17x7.5 wheels.
Many have said 245/40/17 is the tire size to run, but that seems like it would be so pinched and squirmy. Especially with 1,000 lbs or so on each front corner. Anyone have experience with this tire in this configuration?
Otherwise, considering 235/45/17 or 235/40/18.
Just looking for feedback from anyone running these sizes on a 7.5" rim. Thanks 🙏
To properly run a 245 you should have 9 inch wheels. I'm running 225 tires on 17x8 rims on my Miata.
In reply to DeadSkunk (Warren) :
Define "properly" please. I'm running 255/40/17 V730's on 17x8.5 right now and it's fantastic. Responsive and no sidewall roll down to 33 psi. There's definitely an "ideal" range.
But I feel a bit like I'm taking crazy pills about 245/40 because other GTI people in GS are recommending it 😆.
I don't have any experience running tires that much wider than the wheels. All I would suggest is the sticky tires may well feel really good, but until you try narrower ones, with the sidewalls ever so slightly stretched and supported, you won't really know what's optimal. Reading all of the tests Andy Hollis has posted here, he routinely runs 245 tires on 9" wheels. I recall him mentioning that the Bridgestone RE71RS tolerates being pinched better than other tires. As for what other GTIs are running, are they testing to find the optimum, or simply copying each other? The other question I'd seek an answer for is are the Kumho the best tire choice for a FWD autocross tire these days? I don't know , so I'd find Andy's test results and start reading.
Edit: test from a few years ago....200-treadwear tire test | Kumho Ecsta V730 vs. Yokohama Advan A052 | Articles | Grassroots Motorsports
Edit again: Tweener 200tw tires: Kumho V730 vs. Yokohama AD09 vs. Nexen Sport R | Articles | Grassroots Motorsports......in this second article, Andy says the V730 needs a hot out lap to turn it on. I take that statement to mean it won't turn on well on an autocross course.
I'm sure others will chime in, so stick around.
In reply to DeadSkunk (Warren) :
I can answer very confidently the V730's are great on this car at autocross after multiple seasons with them. They're sturdy, can take a lot of heat (important here in Florida), don't heat cycle out early, don't shred when camber is lacking, have provided a good balance for the car, are affordable (same size RE71RS sets are $200-300 more), and can last long enough for the occasional track session. Alas, my question isn't about which tire. It's about finding the optimal size to put on these narrower rims. Not a simple question to answer, I know... I appreciate your input and the links.
I think you're probably right that some drivers are simply copying each other. I don't know who has tested against other sizes. Hence why I'm looking for people with actual experience running these configurations.
And to the point above about them requiring a hard lap to heat up, perhaps there's a strategic advantage to running a bit narrower than the often-recommended 245 width to speed that up...
245/45/17 on 7.5s is the hot setup on ds twins (not v730s, just a reference). We ran 235/18s briefly and they drove fine, and 245/5/45/17 RE71RS and they also drove fine. I know the GTI is a very different car but I wouldn't be afraid to try the 245/17s.
In reply to mrmattolsen :
In your other thread Andy suggested you could put different tires front and rear and swap them around. Would buying V730s in two widths be an option? Then you could try a narrower tire on the front. If it's not any quicker, or even slower, you can put the narrow ones on the rear and get the car to rotate better. Just an idea.
There is one school of thought that says wider is always better for autocross, and that may well be true even for pinched tires. Have at it and let us know , whatever you decide to do.
Since I'm out of touch with current rules, is the 7.5" width a rules requirement?
DeadSkunk (Warren) said:In reply to mrmattolsen :
In your other thread Andy suggested you could put different tires front and rear and swap them around. Would buying V730s in two widths be an option? Then you could try a narrower tire on the front. If it's not any quicker, or even slower, you can put the narrow ones on the rear and get the car to rotate better. Just an idea.
It's not my first choice because then I can't effectively rotate the tires, so I'll burn through the fronts in basically half the time. But I suppose I could get on a replace-2-at-a-time schedule. It's a consideration.
Since I'm out of touch with current rules, is the 7.5" width a rules requirement?
Street class rules. Max wheel width is the OEM wheel width, +/- 1" diameter, +/- 7mm offset.
dps214 said:
245/45/17 on 7.5s is the hot setup on ds twins (not v730s, just a reference). We ran 235/18s briefly and they drove fine, and 245/5/45/17 RE71RS and they also drove fine. I know the GTI is a very different car but I wouldn't be afraid to try the 245/17s.
This is interesting, thank you. Obviously the twins have lighter corners than the GTI, but still good info.
I asked this question in a couple other places, and the answer still seems to be to run 245/40/17 because that's what the GTI guys at Nationals are using. Seems it is part of the formula for trying to keep up with the Civic SI's, which can run a wider wheel and tire.
Most of them are much more experienced than me, so I'm fine with weighing that heavily. But I still can't shake the concern over the pinch factor.
I know a guy locally who has a set of wheels with old RE71 245/40/17 tires on them, so I'm going to mount them up and give it a quick drive to see how it feels.
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