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wheel offset?
10-30-2008, 4:46 PM
is it better to have negative or postive offset? id imagine that if you had negative offset rims up front that you would get more angle wouldnt you? since the hubs is twards the rear of the rim and wouldnt that make the wheels come out more? and then have a zero- sumthin like +25 offset in the rear
The amount of offset you need up front will depend on the width of your wheel. For an 8" wheel you should be fine with around +22mm. To run a 9" wheel, you will want more like +10mm. Right now I am looking at picking up from front wheels 17x8 +20mm for the front of the car.
The rear of the car works well with a +30mm if you have SN95 axels and a +18mm with fox axles.
Of course you can move your wheels even further out, but remember, moving the wheels out up front has a negative impact on scrub radius. A lot of s-chassis guys run insane offset, but they also don't drive their cars to the track.
whats the advantage of runing bigger rims then smaller rims, and there impact on drifting? like 16vs17vs18, tires are hella cheap on 16" rims new.
I am actually interested in trying out some 16" wheels, and some 18" wheels to see what works best on the car, maybe even figure out a way to try all three different combinations on a single track day. That would make a cool video, and I would love to get the data comparing them all.
The basic theory is that the amount of sidewall that a wheel has is going to make the car respond differently. Getting a tire combination that matches your driving style, power output, and car setup is very important. Of course the tread design and compound also make a big difference.
At the higher levels in the sport, guys spend a lot of time figuring out tire sizes and pressures. I have only just started to play around with that sort of stuff.
In my experience of trial and error, my S13 has been at about the same power level (~155whp) for over 2yrs and have tried 15's, 16's and as of late 17's. So far bigger is better. Mainly due to the lower profile. In 15's it was usually a 195 or 205 in a 60, 55, and 50 series; then in 16's it was 205 in either 55 or 45-series; and now it's been 215/45-17. In my own opinion, 16's tend to be just as pricey or more than 17's, also 17's offer a wider range of tire sizes. Example: the 205/45-16 I ran were $61 and the same tire (Federal 595SS) in 215/45-17 are $58. This isn't always the case. And going from 17's to 18's, now that's a decent jump up in price. Most people running 18's in drift it's just for looks, but for grip/track set-up it's for the more rigid set-up, which also could be the case in drift, but probably not.
Here's my observations;
any sidewall lower than 1.5" is too little (for front tires). Of course this is dependant on tire construction, and compound. I experiemented with several diff tire sizes, including 16s with 55 series sidewalls, 17s with 40, and 45 series sidewalls, and 18s with 40, and 35 series sidewalls. From my road racing and autocross experience, I can really tune into my tires, and feel how they are "biting", and when they are breaking the threshold of the traction limits. To me, the 17" fronts, with a 45% sidewal (of a 245) was the absolute best. I run a moderate pressure (around 34-40 (hot)), and check the corners of the tires constantly for "roll-over". More sidewall, equals more roll-over. Less sidewall, equals less flex in the sidewall, creating a lower point of "break-away", which roughly translates to less turn-in traction.
For the rear, I like very low sidewalls. Like the fronts, the less sidewall means less turn in traction. So, if the tire has less sidewall, it loses its forward traction faster than a higher sidewall tire. Less sidewall, also gives you more consistancy of sideways traction. Since there is less flex (in sidewall), there is less of a chance of the tire gaining and losing traction. Its like a skate board on hard or soft wheels, the softer they are, the more traction. The harder, the less. I also beleive the more tire in back the better. Of course low horse-power cars have a harder time spinning bigger tires, but I've run 275s on the rear since year 1 (with only 250hp). Just air them up. On the budget side, 245s can make due. Remember, if you're having trouble breakign them lose under initiation, just air them up. I know from lots of research on this, you can run extremely high pressures. In Japan, they run 60-90 PSI. Yep, not a typo. This IS legitiate info from a very good friend of mine who owns a car and practices in Japan with Kumo-Kubo.
I dont recommend that high, but I never run anything less than 45psi (cold).
As for diamater, I chose 18s cuz they're easier to get wide sizes from a variety of manafacturers, plus they look better than 17s. You can definately get away with running 17s, but again I really recommend lower profiles, 40% of a 265 and lower.
As for 16s- dont bother. Its too much sidewall, and 16s are more expensive than 17s (due to the abundent supply of 17" aftermarket rims and tires).
Just my 2 cents, take it or leave it.
"In Japan, they run 60-90 PSI."
This is at the track of course. Not recommended for street cars. :)
We ran 50+ psi in the rear tires our last time at the Oval Track at Willow. That was with a 245/45R17. It seemed to work well for the stock power level on our car.
I have been starting with pressures ranging from 47-53psi (cold) depending on different tracks. Dont be afraid of this pressure-range when experimenting with your own car. As for 65 + range, you cant even get me to stand near a tire with that much air in it- ha ha!
LOL!
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