RedLeader
Well-known member
Yesterday I decided to attempt to use the break in the weather (Seattle area where a dry day on the weekend is a rare thing in March) to see if I could find the limits of the maximum allowable tire width the Leaf. The maximum tire width is not relevant to anything other than those who may be thinking of attempting to use their Leaf in an HPDE. With the spring coming up and the local motorsports season following, it’s been on my mind. I only did an analysis of the fronts since the rears are a very simple matter which I can do at some other time. I was fully expecting to encounter problems even with mounting but was rather surprised with what I found.
On the right you have the Leaf’s OEM wheel & tire:
Wheel: Enkei OEM - 16x6.5 ET+40mm
Tire: Bridgestone Ecopia - 205/55-16
On the right is the front tires from my track car:
Wheel: Sparco Racing - 18x9.5 ET+35mm
Tire: Nitto NT01 - 275/35-18
The only relevant part of the track wheels for this experiment is the offset. The tire when measured from the outside tire walls is 11” wide, more than 3” wider than the OEM tires. The Nitto’s diameter is about 3/8” larger than the OEM. The Nitto is worn down about 4 to 5/32nds from when it was new. The dia of a 275/35-18 tire is a little too large for what you would want to use, but for the purpose of this experiment it would be able to indicate to me where the limitations are. Something to note; even though my track package is massive by comparison to the OEM, they feel almost identical in weight, my track wheel are about 48lbs when the tires were new.
I mounted the tires onto the Leaf, rolled the car back a few feet and then forward again applying the brakes firmly to make sure that the suspension was compressed properly at what should be normal ride height. Surprisingly even with a 275 tire and +5 mm within its offset there was about 20mm still left between the strut and the tire. This is very much in line w/ the typical Nissan standard of allowing for much larger room in the wheel wells as if they were thinking of putting a much larger package under the fenders. The SUV like suspension clearance around the fenders made it very easy to check for clearance issues and visually the gap between the fenders is still very obvious even with the larger dia tire. It appears that Nissan choose to run the car about 1” higher than what the sheet metal of the body was originally designed for.
Next I checked lock-to-lock. Again I was surprised to what it allowed. Everything seemed to look well.
The only possible problem that I could find in the static check of the setup was that the tire stuck out of the fender about ¾”.
At this point I was confident that a test drive would be acceptable. An EV lends itself very well to dynamic analysis in that its operation is smooth and relatively silent. Increased road noise from the larger contact surface and tire construction was there from the start. As the tires got up to temp, the sound of debris, picked up by the tires, hitting the fender liner was far more audible than in any ICE since it is usually drowned out by the engine. As far as overall grip, it was much more improved as expected. However also as expected, the handling was terrible. Very unbalanced as the rears were all over the place. I’ve never been a fan of FWD cars and that just made the feel all the more unpleasant. As much as I tried to cause some kind of rubbing, I could not. I was surprised but I should mention that I did not get the tires up to optimal temp, I did not hit the bump stops and I was not driving at 10/10th like at an autocross practice.
Does this mean that since the 275 width tires were sticking out of the fenders and there was no rubbing that a 315(or wider) width tire would work? No, at full lock the forward and aft clearances were around 1/2 and inch. This would mean that a tire could probably not be wider than what I ran.
Ideally, it would see a 265 width tire w/ the proper offset fitting entirely under the front fenders on the stock suspension, which may be necessary depending on your class rules and/or if you want to stay street legal. No saying for sure what interference issues would be like if the car was lowered, but initially looks like an inch should not affect it at all.
On the right you have the Leaf’s OEM wheel & tire:
Wheel: Enkei OEM - 16x6.5 ET+40mm
Tire: Bridgestone Ecopia - 205/55-16
On the right is the front tires from my track car:
Wheel: Sparco Racing - 18x9.5 ET+35mm
Tire: Nitto NT01 - 275/35-18
The only relevant part of the track wheels for this experiment is the offset. The tire when measured from the outside tire walls is 11” wide, more than 3” wider than the OEM tires. The Nitto’s diameter is about 3/8” larger than the OEM. The Nitto is worn down about 4 to 5/32nds from when it was new. The dia of a 275/35-18 tire is a little too large for what you would want to use, but for the purpose of this experiment it would be able to indicate to me where the limitations are. Something to note; even though my track package is massive by comparison to the OEM, they feel almost identical in weight, my track wheel are about 48lbs when the tires were new.
I mounted the tires onto the Leaf, rolled the car back a few feet and then forward again applying the brakes firmly to make sure that the suspension was compressed properly at what should be normal ride height. Surprisingly even with a 275 tire and +5 mm within its offset there was about 20mm still left between the strut and the tire. This is very much in line w/ the typical Nissan standard of allowing for much larger room in the wheel wells as if they were thinking of putting a much larger package under the fenders. The SUV like suspension clearance around the fenders made it very easy to check for clearance issues and visually the gap between the fenders is still very obvious even with the larger dia tire. It appears that Nissan choose to run the car about 1” higher than what the sheet metal of the body was originally designed for.
Next I checked lock-to-lock. Again I was surprised to what it allowed. Everything seemed to look well.
The only possible problem that I could find in the static check of the setup was that the tire stuck out of the fender about ¾”.
At this point I was confident that a test drive would be acceptable. An EV lends itself very well to dynamic analysis in that its operation is smooth and relatively silent. Increased road noise from the larger contact surface and tire construction was there from the start. As the tires got up to temp, the sound of debris, picked up by the tires, hitting the fender liner was far more audible than in any ICE since it is usually drowned out by the engine. As far as overall grip, it was much more improved as expected. However also as expected, the handling was terrible. Very unbalanced as the rears were all over the place. I’ve never been a fan of FWD cars and that just made the feel all the more unpleasant. As much as I tried to cause some kind of rubbing, I could not. I was surprised but I should mention that I did not get the tires up to optimal temp, I did not hit the bump stops and I was not driving at 10/10th like at an autocross practice.
Does this mean that since the 275 width tires were sticking out of the fenders and there was no rubbing that a 315(or wider) width tire would work? No, at full lock the forward and aft clearances were around 1/2 and inch. This would mean that a tire could probably not be wider than what I ran.
Ideally, it would see a 265 width tire w/ the proper offset fitting entirely under the front fenders on the stock suspension, which may be necessary depending on your class rules and/or if you want to stay street legal. No saying for sure what interference issues would be like if the car was lowered, but initially looks like an inch should not affect it at all.
That's insane! To think a 275 width tire could be put onto a Leaf? I see this as a very positive thing. There's a couple of "issues" that need to be solved about the Leaf and when/if they are there might be a place of it in grassroots motorsports. Do you have a plan to toss the R-comps from the rear of your track car on the Leaf also to find the limits of the rears? Did you try out the Motegi's yet? If so, how's the car feel like w/ R-comps on all 4 corners? What you're doing is great for the part of the Leaf's image that only a small few on this forum are doing to address. You are improving the "breed" for racing. 
