ok so the speed search continues. I know that in cars that come with say, 16" wheels, when you go bigger the car accelerates slower because because the rotational mass increases and i think the gearing changes somehow. I don't want to assume, so ill ask. Does this process work in reverse? in the presence of logic i would think it does, which leads me to this question. What do you think would happen if i went with a 17" rim. Do you think there would be a noticeable increase in acceleration? do you think there would be a noticeable deteriation in the handling dynamics?, say if i went with a 235 width tire all around (scc says the same tire size all around may actually be the best balance for handeling), would there be a dramatic change in ride quality? well, your future input is appreciated.
by the way im not a particularly big fan of the crossfire's rims on their own, but they do match the car beautifully in that of so industrial yet graceful style of art deco, but this decision is purely performance motivated, not aesthetic, although i can picture some japanese rims that would look great on this car, like some o.z.'s, or buddy clubs. mmmmmmmm..... light weight buddy clubs.

 

X'ed I am going to be doing the same. Yes going with smaller wheels will help you off the line. Am I the only one who feels that it almost like it is boggin of the line. Once your moving the power is good especially in 2nd. It is because or wheels are too Dang big. Im just having a hard time finding a wheel that fits. I found out or pattern is 5x112 with a 35 offset. I want to put on 17's all the way around with some Perelli P Zero M+S. 225's up front for sure, not sure what ill do with the back yet. May keep it at 245's not sure not like it needs the width. The biggest difference in gett in the smaller wheel is you notice is in your 60'. So yes lighter rims will make you "quicker". It the reason why I left my stock 16's on my wrx and sold the aftermarket 17's. For every 10 lbs of rotating mass reduced its like taking 100 lbs of dead weight off the car. just my .02

 

But won't your top speed be reduced? you would need higher revs to go say 70mph with smaller wheels than with larger ones. This would then affect fuel consumption etc.. Doesn't sound like a good idea to me. I would think chipping the engine for faster off the line is a better solution.

 

why runin the design of the car... if you want smaller wheels then buy something else....

Sorry guys, but cant understand the logic....

 

we're not suggesting you understand or logic. thats what makes us different

 

BIG heavy rotating mass is not your friend. I believe the rear tire/wheel combo to be over 50lbs. Try to save a realistic 15lbs per wheel thats 60lbs in rotating mass gone. You will have some more off the line ballz.

 

On the inside of the doorsill in the xfire it says to use no smaller than 18 inch wheels, as I recollect, but I don't know why.

I would like to have smaller wheels too, the same size in front and back. It's more practical, considering the cost and limited availability of replacement tires, especially in the event of a flat ; the new SLK comes with 17s I believe, and I don't see why the xfire at 215 hp and 3100 lbs needs 19" wheels, but I don't understand all the parameters.

 

May I interject an ignoramus question here. I too am thinking about smaller wheels (18" all around maybe) for the winter.

I understand (1) would need snow tires and (2) they don't come in 19" size. I might try to drive with the tires I have, but the first time I can't get up the hill to work. . .

What is involved in replacing the wheels? (Just buy with tires and install?) How much would they cost?

Thanks.

 

if you go to a smaller wheel, such as 17s for the front, you must make sure that the wheel has enough clearance for the brake calipers. The rear brakes are smaller.
Also, you will need higher aspect ratio tires in order to maintain the same (or close) overall diameter or your speedo and other speed related sensors will be inaccurate.
for the front, probably 225-45-17
rear, 245-45-17
most 17" rims are 7 or 7-1/2" wide...so 245s might be too wide for the rim.
Also the stock rear rim is 9" wide, so a 7" wide rim will need spacers or the rear will look really skinny (too tucked in)...and if the offset is too different, it could effect handling and tread wear...

IMO, the 19s on the rear is for looks...they could have in on 18's and no one would have noticed...

FYI-stock rims are
18x7.5, et35
19x9, et22

 

Pajim:

Snow tires and replacing the 19" wheels with 18" for winter has been discussed at length.

Use the search function at the top of the screen and search for "winter tires" and "snow tires".

Basically, I bought four stock 18" wheels and Dunlop snow tires. I also put five 40 lb bags of rock salt in the trunk. If you get new rims with sensors for the tire pressure monitor, they will have to be reset by the dealer. It takes about 5 minutes.

I was able to get around every day last winter, except for two, which really needed 4 wheel drive.

Look on ebay for wheels. They seem to be available regularly.

 

if you can get lighter wheels like the SRTs that would be the best overall look.But you could go lightwieght 18" frt.&rear,try and keep the same overall ht.alittle less in the rear will help take off! Lower rear gears would help also.You would loose some gas miles but not much maybe 2-4 overall.

 

If you do go with smaller rims, you could donate your existing rims to the XFI.

If anyone gets a puncture, the XFI could UPS the rim/wheel to where it needs to go.

In the UK, we could be faced with a 3-day wait for our tyres, as they are not likely to be a stock item.

Just a thought.

 

For some reason, the local tire/wheel store here (a very respected independent wheel and brake specialist, not a chain) told me they wouldn't replace any wheels at all. I think they are frightened of changing anything from factory spec., because you'd think they would want to make a sale. I would rather have a slightly smaller wheel and slightly higher profile tire...the xfire is not that different from the slk and it came standard with 17s. Doesn't seem to be worth the $$, though.

 

that doesn't make sense to me. Changes wheels from factory spec sis done like all the time. Just because our car comes with big rims i dont see why it should be different. like you said, it easily could have come with 17's.

 

Well of course you are right. The tire rack said to get the 17" asa ar1 plus Michelin Pilot Sport 225 45 for the front and 225 55 for the rear. Total price without the pressure sensors is 1663 which isn't too bad considering that 10-15k mi from now I'll have to spend 2k just to replace the tires that are on there now....plus finding a new tire for a spare will be a lot easier. Do you think these will look ok ? Do I need the sensors ?

I'd really like a softer ride and not have to worry about having the car sit for days if I get a flat.

If it makes the xfire drive more like a slk that's fine with me. I was looking for a used MT slk when I happened on the xfire to begin with.

thx,

 

I don't think you'll need the sensors cuz you'll have more sidewall to see if the tire is low on air. How it will look is up to you. And I think all 4 ps2 tires is more like 1000-1100. If you're talking about saving money...I don't see the math. 1100 for new tires. 1600 for new wheels and tires. 3rd set of tires...the 17's might be 800? how long are you keeping the car? Do it for the looks or performace gain (lighter weight). Most of the mods we do are not cost effective...

1600+800=2400
1100+1100=2200

go with the 18"+19" goodyear F1, which are excellent tires and save about 200 when you need to replace the oem tires.

225 55 is not avail in Pilot sport 2, you'll need to use goodyears and the tire is larger than oem in the rear, so your speedo will be 3% slower than your previous speed (which is an acceptable diff) 60mph shown is 62mph actual

 

Yes, well I will be able to sell one set of wheels at some point, but you're right it's not for cost savings.

The tires would be the Michelin Pilot Sport a/s not the 2s. Speedo being off would be odd, same with odometer (?). Well, it's something to think about. I think I would still like the smaller wheels and all season tires better.

 

speedo and odo will be off. Anything that is speed related will be effected. such as abs etc. but generally +/- 3% overall diameter is acceptable...if you go the 17" route...have fun...the xfer won't corner the same as before (if you are an aggressive driver).

 

Over all performance if you do maintain close to the same overall ht. And put good performance tires won't be that much different! BUT your ride roadfeel will change alot smoother feel less bumpy but not soft. The real key factor is using a performance tire again.You might loose 5-10% handling from just a tire & wheel change, you should try M.B. wheels.

 

Well that's would i would like, Dan, exactly. Trade 5 - 10 percent handling for a smoother ride (and possibly better bottom end) from the smaller wheels. I've been told the MB bolt pattern is different, don't know if this is true or not.