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View Full Version : Wheels: Does Size Matter?



MsRN
10-04-2012, 08:13 PM
Sorry for the pun, all! ;). More to the point, I called my local shop this spring to have Pilot Supersports mounted to my pretty 18" D-Force wheels, which you may recall are 'oversized'. I recoiled in shock when they quoted me $1500 installed; apparently, stretching tires onto 18x8.5 and 18x9.5 rims is really difficult. Which jogged my memory: do I recall someone saying that larger rims are purely cosmetic, and that 17" rims are preferable for crossing or racing? It seems I could build a much lighter, tougher, and cheaper set of wheels in 17", and run a square setup (17x8.5) to boot. Am I making any sense, or am I totally out to lunch on this one?

johnrando
10-04-2012, 08:18 PM
I'm by no means a tire expert but I read that type of statement all the time, so I would think you are correct... go with 17's square for cross n racing.

As for the pun:

:chuck

:)

BCS_ZHP
10-04-2012, 08:19 PM
I have nothing to educate anyone on tire stretching, no experience in that vein. Just wanted to say glad to see you back posting around these parts. Hope all has been going well.

toddness
10-04-2012, 08:39 PM
Don't they make Magnum style tires?

Hermes
10-04-2012, 09:42 PM
You are absolutely correct to think 17 would be a proper wheel size. It will clear the brakes, it will weigh less, but you will need to run more sidewall (which will make your ride slightly more comfortable). 18" and up is really for looks, hell I think F1 still runs 14s. Modern GT class teams run 18s only because they need to clear the huge BBK's on their cars

M0nk3y
10-05-2012, 08:51 AM
The reason why you want smaller wheels, is because they are lighter (usually).

Lighter wheels have less moment of inertia, so they spin easier when a force is applied. Less unsprung weight = faster off the line and accelerations.

Might sound crazy, but drop a couple pounds on each wheel, you'll feel it.

JKO_ZHP
10-05-2012, 09:47 AM
The reason why you want smaller wheels, is because they are lighter (usually).

Lighter wheels have less moment of inertia, so they spin easier when a force is applied. Less unsprung weight = faster off the line and accelerations.

Might sound crazy, but drop a couple pounds on each wheel, you'll feel it.

I recall reading somewhere that a smaller wheel gives you better acceleration but larger ones maintain a higher speed or something along those lines

M0nk3y
10-05-2012, 10:40 AM
I recall reading somewhere that a smaller wheel gives you better acceleration but larger ones maintain a higher speed or something along those lines

Now we're getting into Tire Diameters.

Reducing a tire diameter (via profile of the tire) from OEM size will make that wheel spin faster, increase torque. However, you're gears will become shorter and you'll loose top speed.

Increasing tire diameter (with the profile again) from OEM will make that wheel spin slower, decrease torque but increase gear speeds. This will help increase top end (and top end of each gear).

My suggestion, don't change OEM diameter unless you're autocrossing...then it would be preferred to decrease the diameter a bit to gain more torque.

PHZ
10-05-2012, 12:11 PM
1 lb unsprung weight in wheels equals about 9 lbs of "regular" weight.

Lighter load on your axle means quicker acceleration

nike001
10-05-2012, 03:07 PM
OP, you never told us how big/wide your tires are that you're trying to get mounted?

MsRN
10-05-2012, 03:16 PM
OP, you never told us how big/wide your tires are that you're trying to get mounted?

I believe the rears are 265/35 ZR18, and the fronts 245/40 ZR18, mounted to D-Force 8.5x18 front, 9.5x18 rear. I'll check when I get home.

nike001
10-05-2012, 03:28 PM
Well that's some BS.

The shop can't call that stretch at all. Those tire sizes are definitely within spec of your rims. Almost nobody will be able to call that stretch, nor will you even be able to see tire stretch when mounted on the rims.

MsRN
10-05-2012, 04:10 PM
Well that's some BS.

The shop can't call that stretch at all. Those tire sizes are definitely within spec of your rims. Almost nobody will be able to call that stretch, nor will you even be able to see tire stretch when mounted on the rims.

Actually, I believe the exact quote was, 'Well, those tires are a real bitch to mount to oversize wheels; that's why it costs so much.' Based on their usual rates, I was expecting $1200+/-$50 for tires + mounting.

danewilson77
10-05-2012, 04:11 PM
Actually, I believe the exact quote was, 'Well, those tires are a real bitch to mount to oversize wheels; that's why it costs so much.' Based on their usual rates, I was expecting $1200+/-$50 for tires + mounting.

Still bullshit. Maybe you can find somewhere else.

Sent from Williamsburg, VA USA

MsRN
10-05-2012, 04:12 PM
I thought to get competing quotes, but then started to consider a 17" combination. It's just taken me a few months to get back to the Family...:)

M0nk3y
10-05-2012, 04:15 PM
That's well within spec.

245 is the max you should go on 8", so it's not even close to stretching on a 8.5

MsRN
10-05-2012, 07:19 PM
I stand corrected. The wheels are as I described, and the rear tires are 265/35. The front tires, however, are 235/40. How much of a difference does that make?

M0nk3y
10-05-2012, 07:41 PM
I stand corrected. The wheels are as I described, and the rear tires are 265/35. The front tires, however, are 235/40. How much of a difference does that make?

You should still be within spec.

Best advice...get on tirerack and look up the specs of the tire. (Sorry...computer off atm)

It'll show you recommended wheel widths ...and ill put $20 and say you're within that range.

Print out that sheet, bring it to the company and tell them to suck it, and go with your business somewhere else.

Not worth your time.

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