Considering running RPF1's 17x9 and 17x10 as a track set-up.
Would 255/40/17 F and 275/40/17 R work OK????
(meaning from a VDC/ABS standpoint, because of the slightly smaller diameters than stocK)
TIA

 

If it's a track set-up, VDC can be turned off. Regardless, those sizes should be fine, although I love my 275 all-around set on 17x9.5 RPF1s. You could still run 275s on your 9/10 combo.

 

Thanks Scott - always appreciate your expertise with this stuff
I assume you are running 275/40/17 also?

 

I cannot say for sure since I’ve never personally run these sizes on a VDC-equipped car, but I would say you are OK with the sizing you ask about (255/40/17 F and 275/40/17 R).

• Your fronts have an overall diameter of 25.03 (3.18% less than stock), and thus not within OEM specification.
• Your rears have an overall diameter of 25.66 (2.25% less than stock), which is within OEM specifications.

The significant comparison here is that your fronts are not taller than your rears (“shorter rears than fronts” is always a problem with VDC).

The ideal sizing (overall diameter) for the widths you ask about is: 255/45/17 F and 275/45/17 R). Of course these sizes may not be available in the tire brand you are considering.

I really think you’re good to go with the sizes you ask about.

--Spike

 

Yes, you are absolutely correct - 255/45/17 and 275/45/17 would be ideal, but they are "orphan" sizes and not available in any R-comp tires that I can find.
Again though, I appreciate the reassurance that 255/40/17 and 275/40/17 will work without any issues.
Thanks for the input

 

Difference in front-rear tire circumference is 2.5 percent. VDC will be happy.

 

Thanks David

 

Yes sir! 275/40/17 Hoosiers on 5Zigens for track and 275/40/17 V710s on RPF1s for autox. I used to run 255/40/17 and 275/40/17 on an old set of RP02s as well as the 5Zigens the Z came with without issue.

275/40 Hoosiers all 4 on 5Zigens:



255/275 RA1s on 5Zigens (for sale):



275/40 V710s all 4 on RPF1 to come this weekend.

Cheers.

 

i just piced up a set of enkei rpf's in 17x9.5 square setup. running 245/45/17 on all 4. on a vdc equipped car (track car only). this wont give me any issues will it?

also tires were dunlop direzza star spec. how do these tires fair?

 

i got kdw`s on my 17 oems.. front i got 235/40/17 rear 255/40/17 i love those tires so much but when i mounting them i saw the gap on my car.. way too much for me.. i tried to lower it as much as i could ( driveway safety ) not to pleased.. i need more sidewall or bigger wheels...

 

^^^^ yup you need wider wheels , then you can run the 255/40 275/40 combo, but really thats still to short for street driving(great fro track) Just get bigger and wider wheels.

 

255/40/17 275/40/17

 

^ your sidewall looks so much bigger..... you sure those are 40's? what kind of springs you got?

 

40s. Hotchkis springs

 

The total sidewall on a 275/40 is 8.66", or 4.3" for the top and 4.3" for the bottom. A 275/45 would have an enormous 9.75" total sidewall, or ~4.9" all around.

 

^also realize I am black on black so it is more of an illusion I highly recommend this setup, response it flawless on the car, it feels light and responsive. I am no track junkie but if I was to take it to the track I am sure this setup would work well.

 

I tried running 245/45/17's on all four corners, and while tracking the car, the ABS cut out. I flat spotted two brand new tires, and learned a valuable lesson. It may be fine for the street, but unless those rear tires are larger than the fronts, you're going to have problems. Running 225/45/17's up front will eliminate this problem.

To answer your secondary question, the Dunlop Direzza Star Specs are AWESOME. Dry or wet, they are amazing.