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Posted by MU91gsx, Dec 16, 2011
Newbie Forum - Beginner/newbie/general DSM modification questions. First mods, how to run 10's when you haven't run 12's yet, any tech question that doesn't fit in another tech forum.
2 trains of thought here. If you listen to the people that have huge wide tires and running 18s, they will not tell you the 'whole' truth about them...either they are having issues with tire wear or, they had to modify there suspension to keep from having unsaid tire wear.
1) why would you want to put big tire/wheels on your car when they contribute to lower fuel economy, more weight over all, less handling to an extent depending on other factors, and high price involved in doing the swap.
2) concider this...tire wear will not be much of an issue as long as you keep the 'center' over the original 'center' of the tire/wheel combo....Please read about offset and how it affects where the 'center' of your combo is. this will save you a lot of pain down the road
3) personally, you are better off staying with the 16x7 wheel or, going smaller as long as you maintain diameter to keep the speedo accurate. 16x7 with +35 offset is ideal for these cars if I remember stock specs correctly. AWD has to have 4 of the same tires as not to risk any drivetrain damage...
If I were you, I would stick with stock unless you plan to autocross or dragrace the car exclusively...spend your money on light wheels and decent set of tires to go with it that are stock diameter or maybe slightly taller and wider...
Remember the first number is the width...second is the %of the width which is important.....205/55....you can go 215/55 for more grip but, rule of thumb is for every 30mm wider....drop the second by 5....235/50....go google speed in gears calculator and go to town on it to see what I mean.
Hope this helps although may not be what you wanted to hear.
Just to note...as long as the center is maintained, you will have normal wear on your tires for those that will try to say...'my tires wear fine' ..... it is because you maintained the 'center' of your combo and you may not have even realized it....Those in the racing world know exactly what I am saying about the change of suspension to compensate for wider tires and different offsets by changing camber/caster/toe-in.
Here is all you need besides clicking on our gallery.
Wheel Offset Calculator
Custom rims, wheel tire packages for your ride - RIMSnTIRES.com
You have a 95, he has a 91. Not all 2gs even fit the same. Please keep up.
Some stuff, I have to leave to the individual....best way to learn is to look it up or mess with it yourself.
I just gave him guidelines so he does not make the same mistakes I did when I was into that stuff....there are so many wheels on the market now, it just about blows my mind...hate to see people get obsessed on 'widest/biggest wheel' strictly out of looks. I have learned there is more than that....
thanks for pointing him in the right direction and hope he makes a better decision....my talon had 17s and started cupping (bought it that way) put some rpf1 with stock offset and tires and 0 problems now other than my daughter mounting a curb and slightly bending and scuffing one....Kids, gotta love them..
you forgot to tell the op the offset...just any 17x9 wont work. he will need this or will rub or have horrible tire wear....been there done that on other cars I have owned.
I know I could have searched around a bit but I'm just getting a feeling for this new forum and so far so good. Seems the DSM guys are a bit less up their own asses unlike 101% of Hondatech ( yes I have a honda but its a prelude and she has treated me quite well for many year and I love beating on civic's with it. )
Like my rears, at 19" x 10.5" + 27, Volk GT-7, 265/30/19.
I have just about an Inch of poke, before pulling, and rolling the fender. 0 camber, and no unusual Tire wear. I'm also +/- 2 tenths of an inch off stock tire width.
Also on an AWD you can run different Widths, it's the OD that matters +/- on the VC, and keep it within tolerance.
It seems those evo wheels fit just about perfect. 234 or a 245 is what I want all the way around this car. I'm going to have to check your pic's out man to get a better idea of how that looks. Oh and is your car lowered at all, if so how low and with what?
I'm not entirely sure I agree with you.
You shouldn't have any problems with tire wear if all you did was switch to wider wheels and tires. But most people also switch up the suspension at the same time and fail to get it properly aligned, and that's what kills the tires. On a stock suspension, switching won't cause more tire wear.
1)As far as lower fuel economy goes, I haven't noticed much of a drop, if any at all. The tire pressure makes a big difference here. This is also where a proper alignment helps. Your right foot makes a bigger difference than the extra 30mm tire width.
2)The term you're looking for is 'scrub radius.' It contributes to heavier steering and torque steer, but doesn't cause tire wear. Like you said, as long as you stick keep it about the same, you won't notice much of a difference. Expect increased wheel bearing wear if you start going with offsets and wheel widths that move the tire more outward.
3)Smaller? The stock wheels are tiny. A 17" rim to shorten the sidewall and an 8" rim with a 235 are really the way to go for the driver looking for a little added performance on the road. You'll be looking at a +35 to +38 offset to run an 8" wide wheel. Shouldn't have any problem fitting this.
Keeping the speedo accurate isn't usually a big problem. Your speedometer will change by the % difference in circumference. Mine has been off every since I bought my car. As long as you know it's off, and by approx how much, you'll be fine.
Stock size tires are undersized. DSMs are a pretty heavy car for a 215 or a 205, like some were equipped. But more important than the width of the tire is that you buy a good tire. Running a dedicated winter and summer tires is a must. All seasons are for those who are too cheap to spend $100 on some steelies and $300 on some winter tires every 3-5 years.
And back to the scrub radius, that's not what kills tires. It's toe that kills tires, which is exacerbated by more negative camber. And a car with stock suspension shouldn't have these problems. Even a car with an aftermarket suspension should have fixed these problems.
I know I was being picky to an extent on mpg but, it is true if you increase the weight of the wheel/tire combo very much....There is a lot of information on this on other car sites where they have done comparos...I do agree with you on the tire pressure and getting a good tire in general and that was most of the point on that issue...i put 16x7 205/55 back on my laser and got better mileage as the other rims were santa cruz 17x8 215/45 and they were cupping some...mainly due to balancing issues.
that is another thing...most do not get the offset as my santa cruz rims were offset +45 instead of the stock +35 or so....that cause more wear on the inside of the tires as the weight was not centered over the center of the wheel anymore...it was slighly to the inside...my rx8 had similar issues with offset rims that were just +20 or so instead of the +45 the car was made for....wore on the inside with 17s instead of the stock 18s as I did not pay attention to that at the time....rims were practically new and tires were new and lasted 20k miles and I rotate them every 10k...car was in good alignment as well as I had that checked as well...
I agree with the performance of handling with wider tires to an extent...best performance will be had by changing suspension along with tires as tires can do just so much depending on compound and alignment which I do agree with...
As far as the speedo goes....stock tires are nearly 25 inches in diameter...speedos are always off to benefit the maker so, as the tire wears, the speedo is off more and more so that you rack up a few more miles as the speedo and odometer are are saying you are going slightly faster than you actually are....I have an old motortrend that tested many cars and found only bmw, if I remember right, that actually was the opposite and you were going faster than the speedo said. Personally, I would go 10 to 20 mm wider and keep the same aspect ratio so that the speedo will be more accurate for the duration of the tire life so, 225/55 for 16s and 225-235/45 for 17s will be ok as long as the offset is around 35 or so...
My point on this is that most people just go strictly for looks and do not think about performance except for the turbo and what have you but, wheel/tire combos can help you out a lot if you get something more practical instead of all bling...Through lots of trial and error, I personally, would rather have the lighter wheel/tire combo as it does 3 things
1/ you get better acceleration and deceleration as the car's weight is lighter not only at the wheels/tires but over all and can me the difference between rear-ending someone and stopping in time....thank god for my hp+ pads on my rx8...amazing brakes....
2/ you get better handling as you suspension does not have to work as hard to keep the tires on the ground when you have a lighter combo and therefore, can adapt to poor road conditions better with the help of the above mentioned as well
3/ Lastly, give same driving habits, mpg will be slightly better and save money for other things you want done or pay for the new wheel/tire combo relatively quickly.
It is facts on what wheel/tire combo can do. I am not saying that stock is perfect or anything like that...Just saying that if you going to change something on the car like that, take a few things into consideration other than looks.
Your 3 points are true, but there's a certain balance that can be struck.
1)Wider wheels can actually be lighter than the stock wheels. But cheap, light, strong. Pick 2.
2)There are diminishing returns as you go wider and wider. And a new suspension really helps. But if you're going to be buying new wheels and tires, why not get slightly wider ones then upgrade the suspension next? I don't know how many people are driving their DSMs on poor roads that often.
3)Say you save 1 mpg by not switching. And you drive 12,000 miles a year. And gas is $3.75/gal. And you go from 23mpg to 22mpg when you switch.
12k / 23 = 521.7gal
12k / 22 = 545.5gal
545.5 - 521.7 = 23.8
23.8 * $3.75 = $89.25
But it's a balance that each person needs to decide for themselves. I have no problems spending the extra money on gas if it makes driving more pleasurable.
I run 245/40/17 on a 17x8" +38mm wheel. Any "loss in performance" was quickly forgotten as soon as I pulled out of the tire shop and felt how much better they were. That said, I'll be going with 275/35/18 tires on 18x10.5" +12mm wheels for next season. But I autox.
It sounds like you had some alignment issues with your RX8 and your blaming tire wear on your wheel choice.
Awwww. Come on. I know you have something to say on this.
I started to rag on the above yesterday, but gave up and deleted it.
To be blunt, the above is complete nonsense. Offset has no effect at all on whether the weight is centered on the tread. Offset changes whether the weight is centered on the wheel bearing. The distribution of weight across the tread - at least when going straight ahead and all else equal, yadda yadda yadda - is determined by the camber. And offset has no effect on camber.
thought I said bearing....my bad...camber is just the tilt but both work together to a degree...sorry for being too techical....sorry for the wording....glad you know what I was trying to say....
I have seen cars with 'go-cart' wheel/tire combos on them as they get hugely negative with the offset and like the little wheels protruding from the cars....local tire shops love this cause the tires would wear and the bearings would fail quickly due to this combo...it is extreme but is what I meant....camber and toe have most to do with the wear of the tires...offset can disrupt so you have some tire wear as well but, mainly bearing wear/failure.....I have seen a lot of junk out on the 20+ years on the road....I am sure you have too.