[ssfblue]

Does the on-board computer, speedometer and/or tachometer need calibration? If so, would it need to be done by the dealer? How can I retain the use of the tire-pressure sensors?

Currently, I have whatever comes standard... 16" with wheel covers. I would like to upgrade to 18"s but am afraid of how it will hinder performance and mileage if at all.

Thanks!

 

[Goldtouch]

I bought my rims online but stayed with the 16's. Not that it will affect it much but bigger wheels take more to turn them. As for the sensor, I just put the stock ones on the new wheels, I plan on putting snow tires on the stock steel wheels (without the TPMS sensor).

 

[TartanJack]

For the computer, what matter is the overall diameter. It should be as close to "stock" as possible. Too much smaller or larger throws off everything accordingly.

Performance itself is a matter of wheel weight, specifically unsprung weight.
The more weight, the more the suspension must work to give a good ride and compensate for road irregularities.
Also, the more weight, the harder the vehicle must work to get the wheel to either start turning or stop turning. So, in effect, a lighter wheel is like adding a little bit of power and a bit of brakes, while a heavier wheel is like taking away power and braking ability. (Well, not literal horsepower, but it wastes horsepower or "conserves" it . . .)
-That is also why heavier wheels hurt economy too.

Also, heavier the wheels are, it CAN (not necessarily will, but can) affect suspension performance in cornering.
That said, a more "grippy" tire can overcome that fairly easily.

Personally, I like my wheels (rim and tire total) light as possible, with good, grippy rubber on them. Thereby, performance is enhanced rather than hurt.

Oh, my "benchmark" for "help" or "hurt" is the weight of the stock steelies, which aren't as heavy as one might guess. From what I have read on Scion forums, those come in about 20 lbs, so I want LIGHTER rims than that. Also, due to sidewall design, lower profile tires also seem to be heavier too, so take those into consideration.


(The reason I am so concerned on wheel weight is that I come from the Miata-world, wherein wheel weight is a central factor in rim choice. The effect on a Miata of a heavy rim is quite noticeable in terms of performance.)

 

[eviljack]

Ok tartan I got a question for you? Where is it that you can prove that lower profile tires are heavier? There is less sidewall and less rubber. Plus the lower profile adds more to handling then lower weight tires would. So if they are heavier its a give and take type thing.

I will have to go and weigh my wheels now to be sure. Just to find out for fun I am going to take my stock steelies and tires and weigh them against my 18's low profiles.

 

[TartanJack]

The side walls are made stronger.
Give me some time and I'll dig up something . . .

Edit:
This isn't very complete, but is from the main Miata site:
http://www.miata.net/faq/tire_weights.html

This is from a VW enthusiast site:
http://www.gti-vr6.net/library/wheels_tires_brakes/tires_weight.html

I'll look for some more.

 

[TartanJack]

More:
http://www.team-integra.net/forum/display_topic_threads.asp?ForumID=17&TopicID=116506&PagePosition=1


If you look at the charts on brochures (where diameter is listed), many (all, I would hope) also list weight.
In all I've looked at over the last decade (remember, the Miata is VERY wheel -rim and tire- weight sensitive), I've notices a usual pattern:
As the ratio goes down, weight goes up.

From what I remember, it is due to a stronger structure needed to prevent "rolling" of the sidewall, which can cause rim mounting and patch deformation issues. Taller sidewalls can take more flex before having issues, fo they can be made lighter.
Also, smaller ratio tires tend to be wider, which also takes more rubber and structure-> meaning more weight.

-> See, I'm not making this stuff up or talking/typing half-baked (except when I admit as much in my own posts).

 

[eviljack]

I never said you were making it up I just wanted to proof that I was wrong in my thinking.

I still argue that the extra handling and on a wider tire, the greater handling and grip out weigh the extra weight. However I will agree on the miata. Thats one of those cars thats very precise on balance. Not just light wheels but balance all the way around. I bet even a super light weight staggered wheel set up would still handle like crap compared to a not as light weight non-staggered set up.

Anyways. I weighted my stock wheels with stock tires inlfated. No center caps. Total weight 41.7 lbs. I weighed it on with the balance board from Wii Fit. When I get a chance this weekend I will weigh my 18's and see where they come in at.

 

[TartanJack]

Plus the lower profile adds more to handling then lower weight tires would. So if they are heavier its a give and take type thing.

Yep, your right, it is a balance between weight and grippy tires.
Note, my statement:

Also, heavier the wheels are, it CAN (not necessarily will, but can) affect suspension performance in cornering.
That said, a more "grippy" tire can overcome that fairly easily.

The challenge is to maximize grip, while minimizing weight.
That gets done different ways on racing cars, depending on performance parameters needed, desired, and achievable within the rules. In some cases, small rims with high side-walled racing tires are used, such as in autocross and some racing series. On a nice, smooth track, some race teams go for a very low ratio and ultralight (and VERY expensive) rims with racing tires, such as in the American LeMans Series.
In F1, the tires are set by rules, but massive grip is achieved (despite much effort to limit it) on small rims with tall sidewalls.

It all depends on needs, $$$, and what one's aims are.
Oh, and a LeMans style rim would be VERY rough and probably destroyed on a typical street drive, as they have little sidewall to cushion rough pavement breaks from hitting the rims themselves. Yet, they work fine on the track.

One of the things that surprised me on the xB2 is that the stock 16" rims are 55 ratio, which are the highest used by the high and ultra performance tires. So, great rubber is available for them.
The 17s use 45 ratio tires, which is the same stock street rubber for many supercars.

For a street car, it is a balance of ride, weight, looks, grip, and cost.
For me, it is the least weight rims I can afford that a GREAT tire can fit and not make it too rough for the crappy and under-maintained roads I must drive on (I live in a town in the middle of the woods).
In that case, 16s and 17s would work well. Until I find a "must have" rim I want, I'll just run my 16" steelies.


Oh, and (if you look) the steelies (at around 20 pounds) are LIGHTER than many aftermarket aluminum 16s and 17s. That automatically means I'm of very limited interest in those rims . . .

Some black Motegis I've seen are 18-19 pounds and look good (i like very simple wheels) . . . those might get a look!
-If only I could find some 16 pound 17s that I could afford and liked the looks . . .

 

[TartanJack]

ssfblue,

Don't let me put you off nice rims. 18s, if light ones, won't be all that big of a deal.
The biggest note is in regard to how much performance means. If you want ultimate handling, keep it light as possible with rims you like and get good performance tires.
18s really aren't that big for wheels of our size. 19s become more of an issue.
Most people probably won't notice much difference between 16" steelies and 18s.

The main thing is not to get some of the massively heavy ones out there. They look pretty, but will affect performance and mileage to some extent.

More performance is gained by great tires, which are easy to come by right now,
As soon as I can "justify" it, I'm getting some high to ultra performance tires. As I live where it doesn't snow much, I can run "summer" tires year round.

If you want 18s, go for it! Just watch the extra weight (if you want highest performance and mileage) and get some good tires.

 

[eviljack]

Yeah I run 18's and love them. Probably why I don't get as good of gas mileage as some others on here. I average about 26mpg around town and such. However I also went with 8" wide rims which combined with the tires I am using give me a much more profound grip on the road. Just ask bob he knows.

 

[ssfblue]

You guys have any suggestions as to which rims would look good and work well? I'm not necessarily concerned about performance as in handling and such. I am more concerned about the mileage repercussions (if any) and the change in accuracy of the speedometer. Also, I am not exactly sure how I can migrate the TPMS to work with the after market wheels/tires. I was reading the owner's manual and read that the TPMS would have to be registered to the vehicle or something like that. It all gets a little confusing I guess.

So yeah, any suggestions of some good looking 18" (preferably gunmetal/dark) rims would be greatly appreciated... also, low priced would be preferred as well. Those TRD ones they sell at Scion are really nice but pretty expensive. I saw some wheel combos on some online places and they sell them for nearly half the price; however, I am unsure of what I would be sacrificing. My style preference would be the "spoke" style.

Much thanks for your detailed answers so far! I really appreciate it!

 

[ssfblue]

Oh and in terms of tires... I live in the Bay Area where weather stays pretty mild throughout the year, if that helps with suggestions and such.

 

[Geezer]

Tire Rack is a great place to look at wheel and tire packages on your vehicle. You also get boatloads of ratings, technical and pricing information, ratings and reviews. I've bought from them before and been very satisfied. That said, when I put rims on the xB, I found them at Tire Rack,but bought them at the local tire shop. They came within $2 of Tire Rack's price, I didn't have to wrestle with installing the tires and the local shop really appreciated the business.

Another comment or two about oversized tires. I have big wheels and tires on my truck and they really kill torque. Acceleration and holding speed on hills is noticeably worse. The speedometer and odometer are off by about 10%, but I just mentally compensate. On the flip side, the odometer shows fewer miles because of the larger tire diameter/circumference. Every revolution of the wheel covers more distance than the stock wheels/tires would. Gas mileage is not as good, but is not as bad as it may appear because every mile on the odometer is actually about 1.1 miles traveled.

 

[eviljack]

I buy all my wheels from here. Have had nothing but great experiances with them.

www.wheelsnext.com

Also if you remove the tire sensors from you factory tires and install in your new tires, they will work properly. The only time you have to re-program your sensors is if you buy new ones.

 

[SinZz]

hey not to thread jack or anything.. but eviljack. how do you get such good gas mileage?!.. i have 18s too but i get like 20 mpg.. =[ any help from anyone would be nice

SinZz--

 

[eviljack]

When I first got my xB and put them on I only got 23 mpg. Then I found a fix for it.

Drive across country at 80mph. I kid you not. The high speed didn't help really, but the consistant speed did. Stop and go traffic causes lower gas milage as everyone knows. The thing is, the xB's computer learns from your driving styles and adjusts the computer accordingly. So they only way to up it significantly is to drastically change your driving for an extended period of time. I was actually getting 28 mpg across country, driving at 80mph with the cruise control on.

 

[wansuie]

If you upgrade to 18", It will affect the stopping distance; gas mileage; but it will increase your driving speed and performance.
But it willl not affect your speedometer.
i just changed my 16" stock rim(20 lbs) to a 16" O.Z. 5 sprokes(15 pounds); the result is better preformance and better handling.
FYI i bought the rim at www.tirerack.com

 

[TartanJack]

The better handling comes from better tires.
The size of the rim is not all that big of a deal, EXCEPT in the tires that are only available in 45 ratio or lower and not in 55. There are some extreme performance tires that are 45 and lower ratio only.
There ARE high performance tires for the16s (205/55R16).

When people go from steelies with highway compromise tires to high performance tires on ANY rim, the performance, handling/cornering ability WILL be drastically improved.
IF you get 17s or even 18s with a similar overall weight to tyhe stock steelies, braking and acceleration will be basically the same. IF the overall weight is lower, the braking and acceleration will be markedly improved.
The stock overall wheel (tire and rim) weight is about 40-41 pounds (varies based on which stock tire Scion put on a particular vehicle).

So, the IDEAL rim/tire would be a stong, yet lightweight 17 or 18 rim with extreme performance rubber ad smooth roads. Then, your "performance" will be improved in just about EVERY way, plus the looks.

 

[wansuie]

I do agree with TantanJack, if you go to extreme 19" or 20" rim, I suggest you upgrade you brake for better stopping and safety!

 

[KarlElvis]

It's funny, I hadn't thought about the *weight* question WRT new wheels.

when I bought my xB, I picked a set of 18" Motegi Togues because I was in love with the look:

Well, I just had them installed on my black xB and they look badass.

But.

They're really heavy - 25 lbs. And I see a noticeable decrease in gas mileage; like three tenths of a mile per my xB's 'average MPG' readout.

I didn't think to check this in advance. And honestly, they look so bitchin' on my ride, I'm not sure I'd have chosen different wheels if I'd thought about it. But wheel weight is an issue one should consider.