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lightweight spare ?

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Old 10-15-07, 03:07 PM   #16
FormosaSC
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man i took mine out, but then you cant put anything in the trunk or else the board supporting the weight will collapse with nothing to support it... which makes the trunk space useless... andif i try to make a heavy duty board to suport it, i wonder if im saving any weight at all
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Old 10-15-07, 07:44 PM   #17
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I just weighted my spare, and its 48lbs, by getting a lightweight aluminum wheel and the lightest tire, itll be as much weight savings as a C.F. hood. Im shopping around for something light and cheap. I looked at the5-zigen and its 16 lbs. and $200.00.
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Old 10-15-07, 07:48 PM   #18
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Thanks for the pic. on the 5- zigen I wouldnt mind a set of those but not today. Im hoping to get less than 39 lbs. of a Supra spare, but Im guessing you have a big brake set-up Blizzy.
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Old 10-15-07, 09:33 PM   #19
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Quote:
Originally Posted by over40driv View Post
Im hoping to get less than 39 lbs. of a Supra spare, but Im guessing you have a big brake set-up Blizzy.
I do, and I am definitely pleased to have a spare that is actually functional in the trunk.

Getting under 39lbs will not be easy. Most tires are 18-20lbs. For the money, I couldn't beat the Supra spare (I shopped for a single spare with BBK fitment sporadically for some time).

Also, please consider the weight savings effect of non-rotating mass is largely on handling and primarily a result of the moment arm made between the location of the weight savings and the center of mass of the car. The weight savings of a spare tire, so low to the ground, will be less significant than a carbon fiber hood or trunk. Similarly, the weight savings of a CF sunroof delete (I know you have toyed with this) would be even moreso significant.

I guess I say this because spending $300 for a ~15lb difference in spare tire weight is a fringe decision in terms of justifiability (in my opinion).

Because of the low positioning of the spare tire, expect the most significant benefit to not be handling, but rather off the line performance. That being said, expect the performance gain to be no different than the performance loss of having your laptop and briefcase in the trunk.

Ultimately, I think this is why you will almost never see an alloy spare for weight savings. Even a 20lb savings will offer a pretty marginal performance difference. I would rather save up the $300 on a lighter spare and put that toward a CF sunroof delete fund where the difference would be DRAMATIC. It is just really tough to justify the cost of an alloy spare given the location and the subsequent benefit (in my opinion).

I am not trying to hate; I am just trying to offer a point of view.
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Old 10-16-07, 04:21 PM   #20
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Arnt the Supra wheels 17''? If I get serious about the sunroof delete, I would have to check with Lexus to see if I can get a new headliner for a hardtop SC. I appreciate the insight about the center of gravity consideration. I am looking for weight savings for off the line gains. The lighter spare seems easy, but not as cheap or as much as I first hoped. I will have to find the lightest tire to go with the light rim. Mitsguy would probably know.
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Old 10-16-07, 05:32 PM   #21
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Quote:
Originally Posted by over40driv View Post
Arnt the Supra wheels 17''? If I get serious about the sunroof delete, I would have to check with Lexus to see if I can get a new headliner for a hardtop SC. I appreciate the insight about the center of gravity consideration. I am looking for weight savings for off the line gains. The lighter spare seems easy, but not as cheap or as much as I first hoped. I will have to find the lightest tire to go with the light rim. Mitsguy would probably know.
Supra wheels are 17's...so is the spare to clear the brakes.

You can get tire weights at tirerack.com. Generally, Continental, Michelin, and General make the lightest tires around.

As for cost-benefit: 15-20lb of non-rotating weight low to the ground for $2-300 is not great value in my opinion. I'd rather wrap my stock wheels in the lightest tires possible for not too much more. Trimming 2-4lb/tire will have a much more dramatic effect since not only is the weight rotating, but the tire's radius to the rotational center of mass is so long.

All told, I would still pursue the sunroof delete. The high center of gravity combined with the large weight differential would have an amazing effect on the entire personality of the car from a driver's experience point of view.
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Old 10-16-07, 05:44 PM   #22
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Good advice, since Ill be looking at a new set of tires next summer. I really want to do the sunroof delete, but will need to be 100% commited to keeping this car for the long run, and work out the details of a lightweight repl. panel. Also my o.e. spare has never been used, and would then be useless. That being said I will still be checking tire weight and for a good used lightweight 16"" al. wheel.
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Carbing strut tower brace front.
Rear custom made strut tower brace.
Sunroof delete and A.C. delete.
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Old 10-16-07, 05:59 PM   #23
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You were absolutely right Blizzy, 16 lb. tire+ 17 lb. wheel is 33lbs. -48 on the stock wheel/tire a loss of 15 lbs for $300.00. Lot of $ for 15lbs.
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Carbing strut tower brace front.
Rear custom made strut tower brace.
Sunroof delete and A.C. delete.
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Old 10-16-07, 07:01 PM   #24
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If you wait it out you can find great deals on tt spares, I got mine for $40...
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Old 10-16-07, 07:01 PM
 
 
 
 
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