Question about gaining grip (tire related)

My ground control plates are awesome, they make a pretty big difference. I'm running 255/40/17 on a 17x9 et 45 fronts are about a finger or less gap rears are ever so slightly tucked. little rub under heavy suspension loading on the rear fender and needed 3mm spacers on the front to keep them from touching the strut. probably would have been fine but just in case i run them. 245/40/17s would fit easy.

Your car is basically full bolt ons so its better to master what you have then progress to different set up. Cough Cough 17x8 wheels

beauy46 said:

Your car is basically full bolt ons so its better to master what you have then progress to different set up. Cough Cough 17x8 wheels

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I'm not looking to progress to a different setup. I'm looking mostly to see what adding a proper sized tire would do. My setup is almost perfect for the way I drive at the moment, but I wouldn't mind having a tire with no stretch. I think Camber plates are interesting but I won't be adding those any time soon.

Again, I'm not sure that most of the people reading this thread read my initial question.

I REALLY want to know what difference, if any, running a 235 or 245, 40 or 35, 18 would be. Same wheels, same setup, different tire.

FiXXXerX said:

I'm not looking to progress to a different setup. I'm looking mostly to see what adding a proper sized tire would do. My setup is almost perfect for the way I drive at the moment, but I wouldn't mind having a tire with no stretch. I think Camber plates are interesting but I won't be adding those any time soon.

Again, I'm not sure that most of the people reading this thread read my initial question.

I REALLY want to know what difference, if any, running a 235 or 245, 40 or 35, 18 would be. Same wheels, same setup, different tire.

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The wider patch may be worth it for feel(s). But in actual performance gains may be minimal.

Also with current set up would limit how wide and fat tires you could go with. In terms of rotating mass you want lighter (wheels and or tires or both), and wider contact patch to yield performance gains(quicker times and improved dynamics) .

Being 18X8.5 +45 may be a limiting factor
this is a old but still good tire chart
http://www.golfmkv.com/forums/showthread.php?t=59761

How does the WALK kit feel on track? Does the added dynamic camber help at all?

I ran a 225/45/17 on the same wheel im running the 255s on and it is a huge difference. better road feel and feedback while turning in and you can get on the gas much earlier coming out of the corner. Again, not sure if it would translate to faster laptimes on a fast track but i think the difference in turn in and mid corner speed would make a pretty big difference on a tight track or an autocross circuit. I can't speak to the difference you would get on an 18 but i would assume it would be similar.

If it means anything to you i will not be switching back to a 225 and will likely continue running a 255. I feel like it is worth the extra money even as a daily tire.

beauy46 said:

Also with current set up would limit how wide and fat tires you could go with. In terms of rotating mass you want lighter (wheels and or tires or both), and wider contact patch to yield performance gains(quicker times and improved dynamics) .

Being 18X8.5 +45 may be a limiting factor
this is a old but still good tire chart
http://www.golfmkv.com/forums/showthread.php?t=59761

Click to expand...

I wouldn't place much value on that chart in this case to be honest. It's for the stance crowd, it doesn't accurately reflect the fact that you can run wide tires if your car is at a functional ride height.

I've run 245/35-ZR18 Michelin Pilot Super Sports and 245/40-ZR18 Hankook R-S3's on 18x8.5 et45 TE37's for two years now. On a car at a ride height that actually works in the real world and a little camber all around they fit and work perfectly. I have no wheel gap and 2 degrees of camber all around and they don't rub at all.

Without camber they will rub though. If you don't want to do camber plates (which do make noise since they eliminate the rubber top mounts) you could do ball joints instead, if I remember right they add 1.8 degrees. The rear can be adjusted up to 1.5 degrees without camber arms which is enough to avoid rubbing most of the time. I run Integrated Engineering camber plates up front and I'll be buying rear camber arms this year.

I can't tell you that the wider tires will make your car faster. They are heavier so you'll probably lose some straight line speed and they also probably hurt aerodynamics. I run them because I wanted to improve my car's cornering ability, like miami said they understeer like pigs. In my opinion, if you want more speed just crank up the boost, power is so easy to make with these cars that I'll gladly give up some speed for handling.

So what's the real goal here? I'm not sure what you're engine mods are, but with a K03 or K04 that torque is going to give you traction issues on autocross. If your car is pretty much a daily with an autocross session here or there, I'd suggest you pick up a set of cheap 17 x 8 wheels (you really only need 2 for the drive wheels) and fit them with autocross or high quality summer tires and swap them for events.

My GTI is at its stock ride height. I currently run Michelin PSS 235/40/18 and I have no rubbing. I defiantly noticed a large difference in cornering grip over my old Hankook Ventus V12 225/40/18. I realize that the tires are different and that will cause most of the change in grip. Anyways, I am happy with my 235/40/18 PSS's on my 8" wheels. Don't know if this helps...I attached a photo of my car with my new tires. I don't know if the pic helps, but I couldn't resist the chance to show off my car.

Having the camber plates up front and dialing in more camber will really help the understeer and turn-in issues this platform has. Having a stiffer rear with slight rake really helps too. I've done a lot experimenting with camber to dial the my tire temps within 10º from inner to outer.

I just buy pirelli slick take-offs now since they're only $500. I have been buying the hard compound too which works well @summer HPDE events in Socal. I get a lot of heat cycles out of them.

Like SuperSkyline89 mentioned 245 will work fine with about 2º of camber on a 18" wheel.

245/645/18 Pirelli

I'll have some feedback on this after this season. Running a 17x9 et35 with 12.5mm spacers up front and 20mm spacers in the rear. 255/45/17 BF Goodrich rivals, had to run spacers to clear the shocks and also trying to get as wide as possible with fender flares. In theory, the wider stance and wider tires will improve cornering grip significantly but will sacrifice straight line speed. My build is focused on momentum, being able to carry more speed through the turns should more than make up for what I lose in the straights. This is a great thread with some good ideas and looking forward to see what others say.

Das Gespenst said:

I'll have some feedback on this after this season. Running a 17x9 et35 with 12.5mm spacers up front and 20mm spacers in the rear. 255/45/17 BF Goodrich rivals, had to run spacers to clear the shocks and also trying to get as wide as possible with fender flares. In theory, the wider stance and wider tires will improve cornering grip significantly but will sacrifice straight line speed. My build is focused on momentum, being able to carry more speed through the turns should more than make up for what I lose in the straights. This is a great thread with some good ideas and looking forward to see what others say.

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Have you calculated scrub radius? Wider not always better.

I can say it wont be a problem, it actually gives the car some steering feel as appose to the vagueish approximation of feel that they normally have.

Reading your original post, I would tell you that 235 are a no-brainer. I have 18x8 et45 (popular size) and I'm running the 235/40R18. It's a noticeable difference with no drawbacks IMO. Obviously tire manufacturer and compound play too. I also looked at weights when I was shopping around, they vary quite a bit. You may also notice certain models that aren't available in 225 become options in 235 or 245.
Beautiful car btw.