How much grip for 175-200whp?
 

Tried to find a thread on this but nothing quite hit the spot.

My '90 with 1.8 is getting a little baby turbo setup this spring. I'm shooting for 175-200whp and I'm debating on tire/wheel setup. Use of the car will be daily driver with the occasional trackday/autocross/HPDE. I have JIC Magic FLT-A2 suspension ready to go on. 9k/7k spring rates. Currently running 15x6 NB sport wheels. They have tires that are black and round and offer little else.

I'm not very concerned with laptimes. What I'd like to do is increase grip enough so that I'm not spinning the wheels constantly in 1st and 2nd, but not increase grip so much that I lose the ability to stab the throttle and kick the rear out mid-turn. I love how chuckable the car is and I want it to stay that way, just with more power.

I have a potential good deal on 15x9 Konig Dial-ins, and a set of half-worn Toyo RA1s in 205/50 already sitting in the garage. Am I going to have so much grip with this combo that it will ruin the tossable feel the car comes with?

Let me know what you're running for wheels and tires and how much power you're making. What is your favorite balance of grip and fun?

I think at that power level it has been established that anything over 225 r-comps on the track will slow you down. I could be remembering wrong but I am fairly positive that is correct.

That makes sense - what do you think of 205 RA1s on a 15x9 for these power levels?

Should be adequate. I was running 225 rivals on an 8" wheel at around that power level for HPDE and it was fine. The RA-1 has more grip than a rival so I would imagine you would be fine with a 205.

Cool. I went ahead and scooped up the 15x9 Konig Dial-ins and will be mounting the 205 RA1s on them. Appreciate the input.

For a little more fun (less grip) you could go with the Direzza Star Specs ZII in 205/50 on 8". I had the ZIs and it was a blast. Reliable, predictable, lasted pretty long, but definitely not too grippy.

Another vote for the 205 tires. I'm not a big fan of the 225 prices. I also went with an 8" to make the 205s work a little better. 205s on 9" sounds stretchy. When I had fresh star specs and 185hp it was quite glorious with my budget bilstein setup. I doubt anything more would be worth it in the JICs.

I'm picking up what you guys are putting down on the 15x8 / 205 combo. I got a really solid deal on these Dial-In 15x9s or that's what I would have done. I have done some poking around and apparently people are running 205s on 15x9s without things getting too stretched - not really my style, that hyper-stretched gumball look. Apparently it depends on the tire, RA1s are supposed to fare better than some others. When these wear out though I might throw on some S-drives for longer life and a looser feel. I hear RA1s are good almost down to the cords so let's see how it goes. Anyone here running 205s on a 15x9?

The reason for why they might slow you down on track is that the increased aero drag costs you more time than you can make up in the corners. Obviously this is going to depend a lot on the track in question, tracks with only short, low-speed straights will favor more tire, tracks with lots of high speed stuff will favor less drag. For autocross, to pick a fairly common example, the widest tire you can stuff under the fenders (Hoosier 275s) is the fastest one around.

This is all totally irrelevant to what liquidog asked, though. He specified that he was not concerned with lap times, and the implication is that he's aiming more at a street car.

Personally, I would go with 225s of the current hot ST tire (RS3, Rivals, whatever) on 15x9 6ULs. RA1s are not really a great choice as a pure street tire, you never get them hot enough to really use everything they've got. OTOH, if you already own them then you might as well use them up.

--Ian

I would run 245/40 Rival-S on 15x10 for max fun.
225/45 Rival-S on 15x9 for lowest lap time

Let's pretend you had 15x9, 185whp, and you liked stepping the tail out better than good laptimes. Your tire pick?

I'm sorry, I don't understand this concept of going slower on purpose. Perhaps someone else can chime in.

I would go with something like a 225/45 Hankook RS3 or Toyo R1R. Going to a 205 won't just magically make the car loose like I think you are assuming it will - it will reduce front grip by a similar amount. You can make the car more rotate-happy by tweaking toe and rake settings if that's what you're into.

The RA1s would work as well, but if they're old, the car will just push. I would never, ever buy a new set of RA1s.

Nothing wrong with 205's on a 9 as long as they're one of the extreme performance tires like the RS3, Rival, etc. I ran 205 Federal RSR's and they were fine. They'll look better on an 8 though and work just as well.

Thanks for the input everyone. I'll be sure to try some of the summer 225s mentioned here - though I might just use up these RA1s first since they're already there.

Use them up if they're <3yrs old. Older than that, I'd just junk them and go with a summer tire.

I found a deal on 225/45/15 RS3's mounted on 15x9 Advanti Storm wheels. I'm running low boost on a conservative tune, but would guess I'm still under 200hp. I can still spin the tires and kick the rear out if I want to. https://cimg8.ibsrv.net/gimg/www.mia...806cbec407.jpg

Just toe-out the rear about .125"

All the tail-out you'd ever want.

I think they're about a year or so old, so should be ok.