Shimakid12

iTrader: (2)

Heres yet another tire size advice thread. I have a 99 si, and I'm pretty sure that the stock wheel/tire size is 195/55R15. I'm not really planning on doing any hardcore track duty, but I still want a good street size with the potential for a bit better acceleration, grip and maybe occasional racing if desired. I'm leaning mostly towards 16x7 in. wheels with an offset of 42 or 40 (advise here too??). I need a summer street tire and I'm considering the following tire sizes:

1. 215/45R16- I think this seems to be a decent width for the rim and application and the sidewall isn't ridiculously small so ride quality isn't compromised too much. Problem I'm having with it is that I think, but I'm not sure, this wheel/tire size combo is a bit bigger then the stock setup so in theory acceleration will be lost if I'm not mistaken, but I think it is a minor amount.

2.225/40R16- This is a pretty wide tire, which is nice but sort of worries me because I don't want to have any problems with sidewall rubbing, not sure if this would be a problem for this width. Also I think the setup is a bit smaller then stock so acceleration may be slightly better which is a plus. The side wall thickness will be pretty small so some quality may be compromised but I think it will be alright, I've dealt with worse. Also, the overall diameter is like 1.5% different, kind of big but not too bad.

3.215/40R16- This one I mainly like because the width is nice but I think it will offer a slight increase in acceleration due to the setup seeming quite a bit smaller. The sidewall is slightly small and the overall diameter is a big difference though at 2.86%.

4.205/45R16- This one is quite narrow, and may be too narrow for the rim, which is the only main downside, but I think the combo is a bit smaller, so it offers the possibility of better acceleration and braking and the side wall is good. The diameter difference is minimal too, at .77%.

I know there is a lot here, and I apologize for it, but I am putting a lot of thought into this and gathered the info and want some opinions. I have read the FAQ and seen what is generally ideal, I just want a little bit more explanation and advice to back up a certain size and also based on the info I've given about what I want and think, advice with a bit of explanation to back it up is ideal, also if any other set ups are advised please feel free to post them. Thanks in advance guys.

nsxtasy

In 16" sizes, stick with either 205/45-16 or 215/45-16. Both are within 1 percent of the outer diameter of your stock tires, which is perfect (and they shouldn't rub). Both can be mounted on 16x7 rims without problems.

Several of today's "supersticky" ("extreme performance") tires are available in both these sizes: the Bridgestone Potenza RE01R and Toyo R1R in 205/45-16, and the Kumho Ecsta XS and Falken Azenis RT-615 in 215/45-16.

Also, remember that the big factor in performance is the model of tire, not the treadwidth. If the only reason you're considering the larger (16") wheels is because you're looking for better acceleration and grip, you can get that now, with your current 15" wheels. You'll get the best acceleration and grip for those wheels with the Dunlop Direzza Sport Z1 Star Spec in 195/55-15. Other good choices in 15" sizes include the Kumho XS in 205/50-15, the Toyo R1R in 195/55-15 or 205/50-15, and the Falken Azenis RT-615 in 205/50-15 (in that order).

Not only will the 15" tires give you acceleration, cornering, and grip as good as the 16" ones, but they're a whole lot less money, too.

Incidentally, none of these "supersticky" tires is available in 215/40-16, and no tires of any kind are available in 225/40-16 (at least, none at the Tire Rack).

Shimakid12

iTrader: (2)

Hey man thanks a lot, that was extremely helpful. The main reason I'm considering getting a 16in wheels is because, unfortunately, the car did not have the stock si wheels when I bought it. Instead it had some 17 in wheels that don't look that good, and are quite heavy (I can't remember the brand name off the top of my head either...) so I'm deciding to go with some lighter better looking 16 in wheels that will hopefully perform better given a good tire. Thanks for the help, I think I'm leaning towards the 215/45-16's. If the overall diameter is larger do I run the risk of potentially losing a bit of acceleration? Also, any idea if an offset of +40 would be better then +42, or is this just strictly opinion. Thanks.

PatrickGSR94

iTrader: (1)

40 and 42 is only a 2mm difference, probably not enough to make a difference as far as wheel fitment, unless the spokes on one are VERY close to the brake caliper bracket. Then the other offset may or may not fit. Another issue is if the tire is extremely close to the shock or knuckle with the 40mm offset, then the 42mm offset may not work.

There is absolutely no problem running 205 tires on 7" wheels. IMHO 205 tires are a bit wide for 6" wheels, but work great on 7" wheels. I recommend the 205/45-16 size because you'll minimize issues with rubbing at full lock when turning sharply.

I would tell you what offset my 16x7 wheels are, but I can't remember off hand, and the markings are on the back side of the wheel spokes.

Shimakid12

iTrader: (2)

Okay thanks man. I've decided that I'm not so much worried about the 2mm difference in offset and I'm going to look for both 215's and 205's and make my decision based on actual tire specs and price. Thanks for all the help, much appreciated.

nsxtasy

Theoretically, yes, but as a practical matter, the difference is insignficant. The difference in diameter between 205/45-16 and 215/45-16 is only about 1.5 percent.

But as you note later, deciding based on specs, performance, and price is the way to go.

Incidentally, that isn't the same for every wheel diameter. For example, on 16" wheels, 205/45-16 can be mounted on wheels 6.5-7.5 inches wide, whereas on 15" wheels, 205/50-15 can be mounted on wheels 5.5-7.5 inches wide.

For you, though, either 16x7 or 16x7.5 will be perfect, since both widths can be used for either 205/45-16 or 215/45-16, so you can switch sizes at some point down the road if you want to try a different size. (215/45-16 can be mounted on wheels 7.0-8.0 inches wide.)

Here are some of the lowest prices you'll find for each of these tires, starting with the stickiest (although all of these are pretty darn sticky, and performance differences are small):

Bridgestone Potenza RE01R 205/45-16 $172 at Tire Rack
Kumho Ecsta XS 215/45-16 $101 at Tire Rack
Toyo R1R 205/45-16 $128 at TireDeals4Less.com
Falken Azenis RT-615 215/45-16 $99 at Vulcan Tire, $106 at Discount Tire Direct

The Discount Tire Direct price includes free shipping; all the others are before adding shipping charges, which generally run $10-15/tire.

Keef

There's some good tires in that bunch. The RT-615 and XS are the bargains of the bunch, as usual, which almost makes them an easy choice. The Falken is a battle tested hero of autocrossers and track racers alike, but it seem to have fallen behind in the last year or so with so much new competition. For instance, the new Kumho XS has been compared to the great Dunlop Z1 Star Spec and Bridgestone RE-01R in general performance on just about every thread I've read about it here on H-T and on SCCA forums. Not that an inexperienced autocrosser like myself would ever be able to tell the difference. I personally have 205/50-15 RT-615s for my car and was blown away by their performance. I bought them because they were cheaper than all the competition, and still performed with the best of them.

The only problem with tires of this caliber is that here in Ohio I'll have to replace the things every year, even when I do mostly city and highway driving. That's the price you pay for safety and performance.

I personally would recommend the Falken and Kumho, even though it hasn't been tested thoroughly. Both are comparable to the best from the competition and both are much less expensive. Save yourself some money for some big sway bars--you'll need them once you get those tires!

PatrickGSR94

iTrader: (1)

ya because taller sidewalls can stretch to accomodate a larger range of wheel widths.