Aston Martin began offering a ‘Sport Pack’ option on the early DB9s to spice the model lineup after its initial year or two (read the announcement here). The option included:
- Special Wheels with slightly larger tires
- Lightweight Titanium Lug Nuts
- Thicker Front Anti-Roll Bar
- Stiffer Front and Rear Springs
- 6mm Lower Ride Height
The option when introduced was factory installed. What was nice about this was the Sport Pack option could be retrofit to any DB9 manufactured to date by your local dealer. The factory fitted option went for about $4,700 USD (£2,495) back in late 2006.
I’ve been trying to track down the cost if it was fitted by your local dealer. It was sold as the DB9 Sport-Pack Kit that included all the goodies. You can still order it apparently. The kit varies based on model year and LHD vs. RHD. For example, my 2005 LHD Automatic Coupe would be kit Aston Martin part number 4G43-24-10811 available online today for about $8,446 USD. This kit even includes a new steering rack. Later model kits (MY07-09) do not need a steering rack and can be had for a few thousand dollars less. I presume the steering racks unadvertised inclusion on the early models addresses some ‘feel’ issues. These prices don’t include dealer install costs, so I expect a retrofit on an early model to touch $15,000 USD all in. Ouch.
I was intrigued by the idea of tracking down some of the bits for my DB9, and recently I had an opportunity to purchase a like new set of the Sport Pack rims and Titanium lug nuts from one of the readers of this blog (thanks Austin Fritts!).
While I had two full sets of wheels (old and new), I wanted to weigh the difference between the Original and Sport Pack lug nuts and rims. The assumption would be that the ‘Sport’ versions should be lighter right, but by how much? Read on to get the answer.
Reducing unsprung weight is the holy grail of places to save weight (helping handling and acceleration), and you’d think since they included exotic Titanium wheel nuts the rims would be lighter too. While the rims are a different style and they fitted slightly wider tires to them, the rims themselves are the exact same width and diameter as the originals [8.5 x 19 up front, and 9.5 x 19 in the rear].
For both the original and Sport Pack wheels I set about weighing the individual components:
- A set of the four Tire Pressure Sensors
- A set of the four Center Caps
- A set of the 20 lug nuts
- A set of the two front rims
- A set of the two rear rims
I weighed the group of similar items all together and then divided by the number of items to try and minimize measurement errors from the scales.
I used our digital bathroom scale (you won’t tell my Sweetie will you) with a five gallon pale on top of it to weigh the large and heavy rims. It has a display that reads in 0.1 pound increments, so I am going to assume its accuracy is about 0.1 pounds.
For the smaller items I used our digital kitchen scale (again – I need your silence on the issue). It reads to 0.1 ounce increments, and that’s what I’ll assume the accuracy is.
Tire Pressure Sensors
I just moved the TPMS sensors between the rim sets since they are expensive and trained to the TPMS control module in the car. While I had access to them I figured I’d weigh them. The set of four weighed 5.1 ounces (0.319 pounds or 0.145 kilograms). That means each one weighed just 1.25 oz (0.080 lbs or 0.036 kgs).
Each set of rims had a set of plastic center caps. The original rims center caps were plastic with a painted finish to match the rims. The Sport Pack center caps were also plastic with a faux machined aluminum finish (that looks great). Since they are all plastic I didn’t expect much of a difference here.
- Original set of four – 3.4 oz (0.2125 lbs or 0.0964 kgs)
- 0.85 oz each (0.0531 lbs or 0.0241 kgs)
- Sport Pack set of four – 3.1 oz (0.1938 lbs or 0.0879 kgs)
- 0.775 oz each (0.0484 lbs or 0.0220 kgs)
This one is a giant WOW. The Sport Pack lug nuts are Titanium with a polished steel cover on them. The original nuts are the standard steel affair with a similar polished steel cover.
I’ve never had a chance to really experience the difference between Titanium and a matching Steel part. Wow. They are MASSIVELY lighter feeling. Feels like holding a plastic version of the steel part.
- Original set of twenty – 56.8 oz (3.55 lbs or 1.610 kgs)
- 2.84 oz each (0.178 lbs or 0.0805 kgs)
- Sport Pack set of twenty – just 26.0 oz (1.625 lbs or 0.737 kgs)
- 1.3 oz each (0.0813 lbs or 0.0369 kgs)
Both the original 10 spoke Speedline rims the Sport Pack rims are made from aluminum, and are bespoke Aston Martin parts. They are the same overall dimensions, but my presumption was that the Sport Pack wheel design would have some weight savings.
- Original set of two – 51.4 lbs (23.31 kgs)
- 25.7 lbs each (11.66 kgs)
- Sport Pack set of two – 43.1 lbs (19.55 kgs)
- 21.55 lbs each (9.77 kgs)
Same story as the fronts, they are just wider overall.
- Original set of two – 54.3 lbs (24.63 kgs)
- 27.15 lbs each (12.32 kgs)
- Sport Pack set of two – 47.3 lbs (21.45 kgs)
- 23.65 lbs each (10.73 kgs)
Each rear Sport Pack rim is 3.5 lbs (1.59 kgs) lighter combining for a 7 lbs (3.18 kgs) total weight savings.
Complete Wheel Assembly
Since I had the scale out, I decided I would weigh the front and rear tire assemblies of the complete Sport Pack wheels with the standard sized but slightly used Michelin Pilot Sport 4S tires, TPMS sensors and filled to the prescribed 36 psi front and 38 psi rear pressures. The center caps and wheel nuts were NOT included in this total.
- Front set of two – 89.8 lbs (40.73 kgs)
- 44.9 lbs each (20.37 kgs)
- Rear set of two – 101.1 lbs (45.86 kgs)
- 50.55 lbs each (22.93 kgs)
If you add in the minor weight of the center caps (0.775 oz each) and the five titanium lug nuts per wheel (0.406 lbs) the front Sport Pack wheel assemblies weigh 45.36 lbs each (20.57 kgs), and the rears are 51.0 lbs (23.14 kgs).
Since I also know the weight difference of the rims, doing the math can tell us that the original front wheel assemblies (with the heavier center caps and lug nuts) with the same tires and pressures would weigh 49.99 lbs each (22.68 kgs), and the rears are 54.99 lbs (24.94 kgs).
Overall the Fronts are 9.3% lighter, and the Rears are 7.2% lighter. Total weight savings for all four wheels combined was 17.2 lbs (7.82 kgs)
The keen reader would also note that I moved the standard sized tires onto the Sport Pack rims. I plan to use these tires up and change over to the slightly larger sport pack sizes the next time I need new rubber. I would point out that larger tires weigh more and contain more air, both adding more weight counter acting the savings from the lighter materials. A quick look online at the weight of the standard sized Michelin Pilot Sport 4S vs. the Sport Pack sizes:
- Standard Size 235/40 ZR19 – 24.82 lbs
- Sport Pack Size 245/40 ZR19 – 26.57 lbs
- Standard Size 275/35 ZR19 – 27.6 lbs
- Sport Pack Size 285/35 ZR19 – 30.49 lbs
Each front tire would have been 1.75 lbs heavier, and each rear 2.89 lbs heavier leading to an additional weight gain of the rubber of 9.28 lbs overall negating over half of the weight savings of the rims and lug nuts.
But, if you consider the original OEM tires were Bridgestone Potenza RE050A’s, and in the standard sizes weigh more than the Michelin’s I list above (26.0 lbs front, 30.0 lbs rear), you can upsize to the Sport Pack size of the Michelin’s and still end up weighing about the same!
Changing over to Sport Pack rims and lug nuts ends up decreasing the weight on your DB9 by 17.2 lbs (7.82 kgs) overall. In my other article on Power to Weight Ratio (read the full article here) I detail how reducing 8.8 lbs in weight would be equivalent to adding one bhp to the engine performance. Since we removed 17.2 lbs in weight, we’ve done the equivalent of adding 2 bhp of performance and made our DB9 just a little bit quicker.
Working out the cost per horsepower added (as I did in the article) to see if this is a good performance option value (and if I am kind and use the mere $4,700 USD factor fitted option price), that $2,350 USD per bhp. This ranks it as a very poor performance upgrade compared to the other options in the article.
While you can be certain that the Sport Pack option succeeds at dressing up an already fabulous looking car with new shoes, the fact is that it actually makes the car a little faster and lighter, hitting the Trifecta!
But even after all that boring number crunching, what really matters? I got the wheels at a great price and love the look and being able to say at the local Cars & Coffee meets “Those are the Sport Pack wheels. Those lug nuts are Titanium! Ooooo-Awwww”. Ego = Happy.
What do you think about all this? Leave me a comment below.