Project DBA R35 GT-R: Getting More Grip with Advan and Toyo!
One of the issues with the R35 GT-R is that it is a big heavy car that gets an amazing amount of performance out of its tires. The stock tires are a 285/35-20 in the rear and a 255/40-20 in the front. For most cars, this is an impressive amount of rubber but for the 3850 lb GT-R, the car works exceedingly well at first, but the tires quickly fade away. With some ham-fisted driving, the fading away happens pretty fast.
The stock GT-R tends to understeer and overheats its front tires pretty easily, but we addressed much of this in the last segment with our suspension changes. Now to give our GT-R more time before the tires go off, we decided to drastically go upsize in the tire department.
Since the GT-R is no lightweight, we also wanted to keep the weight, especially the unsprung weight low, a hard order to fill especially with tires and wheels that are a lot bigger. The fact that the car comes stock with high quality, lightweight forged Rays wheels makes the challenge even more difficult.
Our new wheel are 20×10 in the front with a 35mm offset and a huge 20×12 with a 20mm offset in the rear. This is up from the stock 20×9.5 with a 45mm offset in the front and a 20x 10.5 with a 25mm offset in the rear.
Look how the backside of the hub area has been cored out. This has been done in the base forging, not CNC cut after forging, so you can bet that there is good grain flow of the metal in this area.
Rays forges the wheel in three stages to get the maximum draw, then as a final stage roll forms the barrel to get the maximum grain refinement oriented around the barrel and to draw it into its final shape.
It would not be possible to die forge the entire wheel as the far side contours would not release from the final die due to the undercutting of the barrel. Most forged wheel manufacturers would simply CNC cut the barrel into its final shape but Rays roll forming is superior for being able to thin out these parts of the wheel while still increasing the strength.