Photos?Over the past few months I've been putting together a set of genuine Audi 20" forged summer wheels for the A8. The forged wheels are significantly stronger than cast wheels and normally lighter as the designs can use less thickness in most areas.
Rather than just buy a set with any old tyres, I have been picking up odd cosmetically imperfect rims from all over Europe on eBay. You would be surprised at the number taken off delivery miles cars with very minor marks. Two have been refurbished, and two I considered to be fine after spending some time trying to find the imperfections.....! Best of all, they averaged out at about £160 per wheel (MRP £500). I have fitted a new set of Goodyear As 3 265/40/20 with my favourite SCT acoustic foam bands inside at a cost very similar to the rims.
The 20"wheel and tyre together weigh 24.5kgs. I figured that they would be a similar weight to the 19" cast alloys on the car from standard.
Today I pulled one of the 19's off the car and checked the weight. It is 27.3kgs with 6.5k mile worn tyres.
That means the car will be about 12kgs of unsprung weight lighter when summer arrives.
Experience suggests that will considerably improve the wheel control and probably negate any ride quality reduction of the slightly smaller side wall height.
I'll wait for better weather to find that out, but I'm very happy with the weight reduction by going up a size in wheels!
Hi Mac. You could start a business with all of us as your customers , apply a 30% uplift and it’s still a bargain.Over the past few months I've been putting together a set of genuine Audi 20" forged summer wheels for the A8. The forged wheels are significantly stronger than cast wheels and normally lighter as the designs can use less thickness in most areas.
Rather than just buy a set with any old tyres, I have been picking up odd cosmetically imperfect rims from all over Europe on eBay. You would be surprised at the number taken off delivery miles cars with very minor marks. Two have been refurbished, and two I considered to be fine after spending some time trying to find the imperfections.....! Best of all, they averaged out at about £160 per wheel (MRP £500). I have fitted a new set of Goodyear As 3 265/40/20 with my favourite SCT acoustic foam bands inside at a cost very similar to the rims.
The 20"wheel and tyre together weigh 24.5kgs. I figured that they would be a similar weight to the 19" cast alloys on the car from standard.
Today I pulled one of the 19's off the car and checked the weight. It is 27.3kgs with 6.5k mile worn tyres.
That means the car will be about 12kgs of unsprung weight lighter when summer arrives.
Experience suggests that will considerably improve the wheel control and probably negate any ride quality reduction of the slightly smaller side wall height.
I'll wait for better weather to find that out, but I'm very happy with the weight reduction by going up a size in wheels!
I really have nothing bad to report. It is still about 50mm too long for the garage, that has not changed. But nothing like as long as my son's Crafter race van which is currently staying with me as the cottage he is temporarily renting is is actually shorter than the van...
The first post I have ever read on this forum extolling the dynamic benefits of lower profile tyres!
If @Mactech A8 has air suspension then perhaps that reduces the impact upon ride, but allows the benefits to be noticed.
Yes, the big caveat here is that these wheels actually reduced the unsprung weight, the exact opposite of most aftermarket larger rims....
Our German mate Herr Suspension has a good part to play in controlling the ride on larger wheels in so much as Mercedes would only supply ML's with 21" rims with Airmatic, a good clue as to what the development engineers found.
Talking of unsprung mass..... is there a preference on race cars for brake calliper location and does it vary front to rear (assuming their location isn't dictated primarily by aerodynamic concerns)?
Yes! In an ideal world they will be inside the wheelbase and as low as possible. In the real world they tend to dictated by suspension pick up points and aerodynamics whilst retaining the lowest possible C of G.
At the front, whether they are ahead or behind the steering axis will make them either detract or contribute (respectively) to the steering effort in a turn due to their own mass being acted on centrifugally. Is the effect significant? And even if it is and unavoidable - does it fall into the 'we pay a driver to deal with it' category?
Relative to the loads from the tyre on the steering effort the effect is minuscule.
...amongst many other things....
