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Even if they weren't revalved, no valving is so consistent that their forces are guaranteed to be the same for a given setting, best to get the shocks profiled on a dyno so you know what your clicks are actually doing. Whoever revalved them for you should have provided you with this information. If not you likely have a nearby shop that can make you a full spectrum plot for a reasonable cost. You invested in the equipment, you might as well find out what it's doing for you.
So I recently picked up a set of old sti wheels 17x8 +53 and will be using 245/40-17 tires. Their offset is 3mm inboard of my rx8 stockers. So I was thinking about getting 3mm spacers to correct that...
I've read a bit about how changes to scrub radius can have an il effect on handling and even enough to negate some of the benefit of using wider rubber. So I was curious with my change in tire diameter from 659mm to 628mm what would be the change in scrub radius.
I found in the workshop manual that the steering inclination angle is 10.5 degrees. Some basic trig told me the new wheels need to be sucked 3mm to keep the same scrub radius. Hey what do you know my new wheel offset gives me that 3mm I need!
If the bore is too small, you should be able to get it milled out pretty cheaply. I had a set of old (now discontinued) Enkei RPo2's that were 42 mm offset and I had the face milled 1.65 mm to make them stock legal on my 8. So the bore should be easier, I would think.
I talked to a machinist who said he'd do it for $40 a wheel, which seems excessive, I mean I could throw a forstner bit in a drill press and douse it with lube and get it good enough to fit and just be lug centric for basically free. And he said he couldn't guarantee concentricity, what kind of **** is that!
EDIT: It seems Nissan Frontier Guys do this sort of thing to fit Titan wheels onto their over-sized hubs. So I'm just going to get a 1/4" rabbiting bit, a lot of beeswax and a broom and just bore it out myself. I need the bore to be 5.5mm more radius and the 1/4" bit will get me 6.3mm, close enough, I'll just be sure to use the lug nut taper to center up the wheels whenever I put them on. We'll see what happens, hopefully these work for a long time and dont fail spectacularly at the first corner, first event.
FOLLOW UP: Everything was going fine and then I guess I held it wrong and it jumped around the hole and bent my $23 bit :-( It was the last one in stock and the roads are all snow covered. I think I'm going to relax and sip some hot chocolate instead.
EDITED FOLLOW UP TO THE FOLLOW UP: I got another bit having learned my lesson about applying pressure radially and being slow and careful, got the first wheel finished without incident, 3 to go, whew!
Last edited by Nathan Atkins; 03-06-2015 at 11:24 PM.
I got all the wheels bored out and mounted, Progress Tech front sway bar is on in the middle setting, all the fluids and filters are fresh/bled/checked etc. and the first event is 13 days away :-)
very excited for the new season.
All that said my low compression engine is a bit wheezy, but I'm running out of preseason so It may end up being a midseason rebuild rather than a preseason rebuild
preseason Virtual dyno
overall tire diameter is down an inch to my old 245/40/18, but there are advantages to effective gearing and the wallet
So, has anyone tried to put 255's in any of the popular tires, i.e., Hankooks, Rivals, etc., on 8" rims? How do they fit if you have?
Would one of the makes of tire be better in this situation than any other because they have a stiffer sidewall? Do you need to run higher pressures to strengthen the sidewalls?
I was cautioned against using 255's by a guy who did on his WRX with 17x8 wheels.
Ideally even a 245 aught to have a 8.5 in it, but cest la guerre, this is street class. I wouldnt go wider than the 245 but whatever size you use adjust pressures according to the load index and then fine tune with a pyrometer from there.
There are a whole bunch of new and new-ish 200TW street tires to consider, but in my view none have presented a distinct disadvantage, so I'll just buy whatever has a good deal going for it, with a slight preference for Rivals only because they're non directional and I don't have to think about what side I'm on when I'm installing them.
Really I think tires just become something to second guess or blame for a poor performance, Ive seen anecdotal evidence coming in through facebook and forums and I haven't seen anything that says any of the new crop are "it" tires.
But if they keep getting more expensive I'm jumping over to the R-comp camp, the new Rival-s are over $1100 in 245/40/18 shipped from tirerack, another hundred bucks and youve got yourself a set of locally sourced 275/35/17 Hoosier A6's :-/
most say don't do it, but a few have been successful with it, pedalfaster/Steven Hui was pretty competitive running oversize street tires when the stock/street tire thing started
back in the real R tire Stock Class days 285 and even 295 on 8" was not unusual, some people feel the typical street tire carcass and treadface design doesn't support doing it that way though
given all the new tire options it could be anyone's guess at this point,the old old BFG groove of doom R tires were specifically designed for being stuffed on a rim, you never know what some crafty tire manufacturer may come up with ....
Last year I raced a mustang gt in fs class at one event with a 17x8 rim and ran hankook ventus rs3 v2's with 255's all around, the tires fit well and performed great I ended up 6th overall against all the street tire classes... just behind a couple rx8's and 350z's. This year im looking to be at the top with my new properly setup rx8.
Last edited by codesterb91; 03-17-2015 at 11:15 PM.
Had my first event of the year and had a codriver, an old RX-8 guy some of you guys might remember, John Vitamvas.
He said the car was a bit down on power which I had expected, he said that the car had alot more movement to it than he was accustomed to on degassed konis (I'm using monster truck modded Bilsteins because hey, thats what I got)
We had a good time and finished 1-2 in the class, he got the winter rust knocked off for his final run and walloped me by over half a second after I choked and coned my last run :-P It was a good battle though, we were neck and neck after run 3:
Looking forward to getting out in a few weeks in marka's old car. Starting out on the RS3 v2's.
Has anybody ran any of the new tires?
Rich
Yes. See the STX thread. I tossed on some Z2SS, and really like them. We had a bbunh of news tires out on a bunch of different cars. Seems the favorite may be the Re71r, but those appear to be wearing very quickly.
Looking forward to getting out in a few weeks in marka's old car. Starting out on the RS3 v2's.
Has anybody ran any of the new tires?
Rich
I put the new 255 V2 RS-3's on my RX8 on 17x9" (STR Miata) rims and it's taken me about 30 runs on concrete with dual drivers to get them working as well as the last year's 245mm Rivals on 18x8" factory rims which I still have.
They wear very well but I don't see any low temp advantage over the old RS3 V1's I had a couple sets of.
Now if you have a dual purpose car and drive to work on them here's a thought. I put a set of 300 wear Michelin Pilot Super Sports on my C5 Vette Z51 with extreme alignment which I autocross routinely but don't go to the big Tour events anymore. These tires are awesome in all weather and surfaces. They can survive track days too. I stay even or faster than people still running 140 tires and beat everyone in the rain for FTD street tires last month in FL. I'm 68 so don't have mad reflexes either. Vette is bone stock with 62k miles normally finish in top 3 against new STi and Z06 C6. Have 55 runs on these tires and they are getting better as they wear down to 5mm now. These tires carry a factory wear warrantee for 6 years up to 30k miles or 15k if you run different sized rims like my vette. That's just nuts to have that available. Of course "racing" negates the warrantee but these tires don't roll over to indicate abuse if you dial in decent neg camber and toe. I figure I'll get two years out of these tires which cost about the same as all of the 200 tires I can fit per set but will last at least twice as long making them a real bargain!! Great selection of sizes from 17-22" rims. Nice that I can still get factory sizes so my handling computer won't go nuts while driving on the highway.
They are quiet on the highway too!! Just a thought. I have convinced (thru performance and top finishes) quite a number of casual autocrossers to get these tires. They just finished a $70 rebate offer which meant free shipping from TireRack. Worth a look!!
my understanding is that fitting the over-width tires has all to do with sidewall stiffness.
I'm wondering if I can take my 12 ton press and put one of those tongue weight scales in it and compress the wheel and tire assembly enough to measure tire spring rate and would that be a good indication of sidewall stiffness.
I feel like this would add an element of credibility to something which is typically word of mouth.
Having driven both Michelin PSS and Continental Extreme Contact DW (not DWS) I'd recommend the Continental. They might have similar performance, but the DW provides better feedback and confidence. Neither is up to the best ST tires in the dry, they are much better in rain conditions though. I run the DWs on my Civic Si street car.
Having driven both Michelin PSS and Continental Extreme Contact DW (not DWS) I'd recommend the Continental. They might have similar performance, but the DW provides better feedback and confidence. Neither is up to the best ST tires in the dry, they are much better in rain conditions though. I run the DWs on my Civic Si street car.
Always appreciate your feedback. Great to have tire options. I'll try a set of these next time. I like the D W wear depth indicators cast in the tread. Great idea.
Here's my fastest run from my last autocross before the motor refresh, I got a good lashing from John Vitamvas in my car to the tune of 0.554 seconds.
Nice looking run. I'm probably not the best person to critique, but I'll throw in my $.02.
What seems to separate the decently quick from the really fast is speed and accuracy of finding the limit.
There is a certain slip angle that a tire gives peak performance at. Ask not enough, and you're leaving grip on the table. Ask too much, and grip falls off.
There's also a certain rate you can load a tire up at. Input too slow, and again you're leaving something on the table. Too fast and you shock a tire and make it unhappy.
The end result is not too far off from singing - a good singer is able to find the appropriate note quickly and accurately. If you watch onboard videos of someone like Heitkotter or Braun their hands are very quiet - they dial in lock quickly and assertively. They also make very few corrections or adjustments mid-corner. Braking and throttle are equally important, but tough to tell from a video.
It takes time and a LOT of practice, but being to push right up to that limit, quickly, is the goal. I'm not particularly successful at it, but there is a definite feeling of when you've got it right. Keep chasing that feeling.
As far as your video, looks like you're moving your hands a little slow in some parts, and a little too fast in others. You're also a bit wide off line in a few spots. But overall pretty darned good.
Thanks Burglar, that all makes good sense and I'm sure it will come with more practice and refinement. Going back and looking at my stuff with an eye towards improving seems to be valuable, and looking at video from guys like Heitkotter are good for comparison.
One of John's pieces of advice that I tend to see in the videos of really good drivers is "Don't drive around stuff, drive at stuff" One weird visualization thing I came up with for that is imagine there is a big hook just outside the rear wheels that you want to catch on the cone on it and swing around. Sounds silly but it's helped me with 'backsiding' and I think I'm going to do much better on April 19th.
Hopefully I'll be in my car and not the wife's BRZ, my rebuild is in progress (both rotor housings were chipping chrome and I had a broken side seal as well as a ton of packed in carbon in the exhaust ports. (ive got pics of everything public on my facebok page if youre interested)
03-01-2015, 05:02 PM
