Light(er)weight Tires

[Lindy]

Perhaps a strange question, but has anyone ever taken the time to compare tire weights? I have noticed differences of 1-2 lbs. in terms of unmounted weight with racing tires for my other (non-Porsche) cars, but have never found a good, accurate source for comparing weights for street tires. I have checked with customer service at Tire rack, etc., but it did not sound like the weights were very accurate.

It would be nice to reduce even a little unsprung weight during the next tire change.

Thanks,

Lindy

[KTL]

Bill Verburg has noted tire weights on a number of occasions. You might ask him if he's got a document containing all the ones he's shared with us.

[RWebb]

Porsche's engineers took the time to compare tire weights and it gave them some ideas about what to not waste time on re the unsprung weight.

It would be great if you located some light wt. street tires...

[Bill Verburg]

Michelin Sport Cups are among the lightest street legal tires out there

[RWebb]

Pilot Sport Cup? does not seem to be avail. in a 15" size

[Flieger]

Tire Rack puts weights on their site. Probably pretty accurate considering they ship them.

[KTL]

Sport Cups are becoming few & far between in smaller sizes. Any idea when a next generation tire is forthcoming?

BFG G-Force R1 are significantly lighter than most comparable tires (and their load ratings reflect this) i've handled & checked weights on. However i'd not consider these street legal, despite their DOT compliance.

[Joe Bob]

According to Tire Rack, 14, 15 and 16 inch tires in sport sizes are being phased out. You get what the manufacturers "feel" like making.

[Flieger]

I use the Yokohama Advan A048. They come on the Lotus Elise/Exige, which still use the 15 or 16 inch wheels. I use 205-55-16 and 225-50-16

[Joe Bob]

Let me add to my above comment.....45 series tires are the biggest casualty. 50 series and taller still seem to have an adequate selection.

[Bill Verburg]

Originally Posted by KTL

Sport Cups are becoming few & far between in smaller sizes. Any idea when a next generation tire is forthcoming?

BFG G-Force R1 are significantly lighter than most comparable tires (and their load ratings reflect this) i've handled & checked weights on. However i'd not consider these street legal, despite their DOT compliance.

They've just released a semi successor, "Super Sport" again only in larger sizes. Tirerack only has 20s for now,

initial releases are, listed below and it's not really an R tire more of a cross of the PS2 and SC but initial reviews have been very positive for track use, at least as good as SC in the dry and far better in the wet

225/45 ZR 18 (95 Y) XL
245/45 ZR 18 (100 Y) XL
245/40 ZR 18 (97 Y) XL
265/40 ZR 18 (101 Y) XL

225/40 ZR 19 (93 Y) XL
225/35 ZR 19 (88 Y) XL
235/35 ZR 19 (91 Y) XL
245/35 ZR19 (93 Y) XL
255/35 ZR 19 (96 Y) XL
265/30 ZR 19 (93 Y) XL
275/35 ZR 19 (100 Y) XL
275/30 ZR 19 (96 Y) XL
295/30 ZR 19 (100 Y) XL
305/30 ZR 19 (102 Y) XL

235/35 ZR 20 (92 Y) XL K1
255/35 ZR 20 OPEN ZR
275/35 ZR 20 OPEN ZR
275/30 ZR 20 OPEN ZR
285/30 ZR 20 (99 Y) XL K1
285/30 ZR 20 OPEN ZR
285/25 ZR 20 (93 Y) XL
295/25 ZR 20 (95 Y) XL
295/35 ZR 20 (101 Y) K1
295/25 ZR 20 (95 Y) XL
315/35 ZR 20 (110 Y) XL K1
345/30 ZR 20 (106 Y)

255/30 ZR 21 (93 Y) XL
265/30 ZR 21 OPEN ZR
295/30 ZR 21 OPEN ZR

295/25 ZR 21 (96 Y) XL

235/30 ZR 22 OPEN ZR
265/30 ZR 22 OPEN Z

The issue w/ all the R rubber sold in Europe was green laws banning the use of some of the better R rubber compound components, all the R rubber sold in Europe has had to be re-engineered, This has been most noticeable at Michelin where the 15 and 16 and now 17s have totally disappeared from the SC line over the past 2-3 yrs, I expect 18s to be gone soon.

[gtc]

RWebb, do you have any weight #s for that graph of yours?

[RWebb]

swapping to Al banana arms only reduces the effective unsprung wt. by 3%
swapping to a lighter caliper will reduce by about 0.5%
getting rid of the cast iron rotor (with say a 5 lb. rotor) would change from 86.2 lb.s to 79 lbs, or 9%


let's see if it will paste ok...

--- Front --- --- Rear ---
Wt (lb.) % of total Wt (lb.) % of total Item
13.0 15% 13.0 15% Wheel
22.0 25% 22.0 25% Tire
- 0% 13.5 15% 1/2 CV joint assembly
3.1 4% 6.0 7% 1/2 R Bilstein shock absorber
13.0 15% 12.9 15% Brake Rotor Disc
0% 7.0 8% Caliper, "M" type
0% 13.8 16% 1/2 bannana arm w/hub (steel)
51.1 88.2

[Flieger]

The things further from the pivot like the caliper have more effect when you look at inertia. The tires and brake rotors have lots more effect on acceleration and braking since they are rotating and the tire is the furthest out from the hub.

[KNS]

Heavy tires (and wheels) will affect acceleration...

[Flieger]

Originally Posted by KNS

Heavy tires (and wheels) will affect acceleration...

Is there an echo in here?

Braking is deceleration, so they effect braking, too.