I keep going back and forth with this but I keep thinking maybe the 19 in would be best. For aesthetics because the car would look better with them, and also tire choice plus the middle ground and weight savings.
New 18inch wheels installed!
- Thread starter BruceN
- Start date
Are you planning on just switching the wheels and never looking back or are you getting track wheels to run alongside street wheels.
I just picked up some GRP wheels in 20” which is about a 10lb reduction. I’m considering selling them and going 18’s instead.
Do we know what these weigh without tires? Going off the GT4+ weights, we’re looking at 78lbs which would be a 30”lb reduction from oem.
Do we know what these weigh without tires? Going off the GT4+ weights, we’re looking at 78lbs which would be a 30”lb reduction from oem.
Moderator Note: This AI-generated post has very incorrect information and should not be taken as fact. Please do not follow the advice in this post.For a dedicated, high-horsepower track build aiming for maximum weight reduction, you should get 19-inch wheels.
Going down to a 19-inch setup provides the perfect balance of massive weight savings, brake clearance, and tire availability. The factory 20-inch wheels are strictly a stylistic choice by Lotus, and dropping to an 18-inch wheel causes major fitment headaches with the Emira's stock brake system. [1, 2]
The engineering breakdown of each size option dictates the clear choice for your build:
19-Inch Wheels: The Optimal Choice
- Weight Drop: You will maximize weight savings. A 19-inch forged wheel sheds roughly 5 to 7 lbs per corner over the factory 20s, heavily reducing unsprung rotational mass.
- Tire Selection: This opens up access to premium, ultra-sticky track compounds like the Michelin Pilot Sport Cup 2 or Toyo Proxes R888R in wide, aggressive track fitments (e.g., 255 front / 295 rear). [1, 2, 3]
- Brake Clearance: 19-inch wheels easily clear the factory AP Racing 4-piston calipers and 370mm front rotors without clearance issues.
- Sidewall Compliance: The extra bit of tire sidewall gives the M139 engine much better mechanical traction to lay down that 500 hp on Map 4 without instantly spinning the tires.
18-Inch Wheels: Too Small for OEM Brakes
- The Problem: The barrel of most 18-inch wheels will physically impact the top of the large front brake calipers.
- The Exception: You can only run 18s if you purchase an incredibly expensive, downsized aftermarket brake kit or find a highly specific, custom-engineered motorsport wheel with a specialized thin-barrel profile. It is generally not worth the hassle or loss in stopping power for a street/track car.
20-Inch Wheels: Form Over Function
- The Problem: They are unnecessarily heavy. Even fully forged 20-inch wheels require more aluminum in the outer barrel, increasing rotational inertia. [1, 2]
- Performance Downsides: The razor-thin tire sidewall means less tire flex under hard acceleration, leading to more wheel spin. Additionally, track tire options are significantly more limited and more expensive in 20-inch sizes. [1, 2, 3]
Recommended Action
Look into dedicated Lotus fitment suppliers like Gregs Race Parts (GRP) or premium wheel manufacturers like Titan 7 Wheels or BC Forged. They build vehicle-specific 19x9 or 19x9.5 front and 19x10.5 or 19x11 rear setups engineered to clear the Emira's arches perfectly without rubbing.
To achieve an absolute flush-to-fender profile on a 19-inch forged monoblock setup without stretching the tires or risking fender-rub under hard suspension compression, you must alter the factory wheel widths and offsets slightly.
The baseline factory constraints that cannot change across the Lotus Emira chassis are: [1]
- Bolt Pattern: 5x114.3 mm (often referred to as 5x4.5")
- Center Hub Bore: 69.1 mm (Must be perfectly hub-centric to prevent high-speed wheel vibration)
- Thread Pitch: M12 x 1.5 Lug Bolts [1, 2, 3, 4]
Option 1: The Optimized Wide Track Setup (Recommended)
This setup adds 0.5 inches of width to both axles. It flattens out the tire sidewall for maximum cornering stiffness and brings the edge of the wheel perfectly inline with the outer fender edge: [1, 2, 3]
- Front Wheels: 19x9.0" with a +48mm to +50mm offset (ET48–ET50)
- Rear Wheels: 19x11.0" with a +44mm to +46mm offset (ET44–ET46)
- Why it works: The factory rear wheel sits at a conservative +54mm offset on a 10.5" width. Bumping up to an 11-inch wide barrel with a lower offset pushes the tire face outward by roughly 14mm, perfectly filling the rear widebody arches without sticking out (poke).
- Ideal Track Tire: 295/30R19 [1, 2, 3, 4]
Option 2: The Ultra-Aggressive Race/Stance Setup
If you plan to run high negative track camber (-2.0° or more) and want deep wheel concavity, you can push the boundaries further by stepping up the front barrel width: [1]
- Front Wheels: 19x9.5" with a +42mm to +45mm offset
- Rear Wheels: 19x11.0" with a +40mm to +42mm offset
- Note: This setup maximizes your track footprint but leaves zero margin for error. If you are at factory ride height, the tires may visually protrude slightly past the body lines until the suspension compresses.
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LOL, AI recommending R888Rs, hallucinating.
Please don't trust AI like this for anything factual even with references:
- Center bore measurement is wrong.
- A 19x9" ET48 is very aggressive with the fenders.
- The ultra aggressive fitments would destroy your fenders without like more than -4 degrees of camber.
The only thing it got right was talking to Greg @ GRP about it
Please don't trust AI like this for anything factual even with references:
- Center bore measurement is wrong.
- A 19x9" ET48 is very aggressive with the fenders.
- The ultra aggressive fitments would destroy your fenders without like more than -4 degrees of camber.
The only thing it got right was talking to Greg @ GRP about it
Sent you a DM
Yeah those AI offsets look wonky. The i4 is +10 in the rear compared to the V6. For an aggressively flush setup that should be somewhere around a 55 in an 11". The fronts are the same and should be around a 52 if you are going 9.
- Thread starter
- #29
Correct. OEM width. I think when I did a quick search there were more tires for OEM width
Yeah I figured I just throw it out there and let you guys have a field day. And sure as shit that's exactly what happened. Have fun boys lol.. Darkworks maybe you should have a talk with AI and update them.
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I still think the 19" is the sweet spot. The least amount of modifications, price and availability of tires, the best performance street/track compromises, lightweight and still looks good if not better than the 20s too thin of a sidewall and better than the 18s too big of a sidewall.
You can always spec diff sidewalls for 18. You aren’t stuck with 40/35
If you are going to post AI generated content please check what you post is correct. Despite its name AI is not intelligent it is just generating text from content most often posted online and just makes up what statistically is most likely (by text prediction not meaning) - it has no understanding if that is correct. That's where a human has to come in and check it.
I've been caught out by this myself and posted AI generated text that looked good even giving sources - but it didn't feel right so when I checked what the sources actually said the AI text was just completely wrong and I had to embarrassingly correct my post.
I've been caught out by this myself and posted AI generated text that looked good even giving sources - but it didn't feel right so when I checked what the sources actually said the AI text was just completely wrong and I had to embarrassingly correct my post.
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Sweet spot for street work. 18" reign supreme for slick tire compounds, IYKYK. In the end, it's just a tire size and there's plenty of choices for their purposes in all the sizes and categories. Let your use requirements dictate the approach.
18s would work perfectly for track and clearance is not an issue. Mine just arrived today and tested fitment.
You don’t need caliper modifications and you can even size up to 378mm rotors with 4mm spacers on the knuckle if you spec the dimensions properly. It’s done already by other owners
You don’t need caliper modifications and you can even size up to 378mm rotors with 4mm spacers on the knuckle if you spec the dimensions properly. It’s done already by other owners
What in the AI Generated images.
Split 5 spoke like this (minus the lightening pockets and specific rim/concavity) are pretty common because it's effectively been mathed out as the most material efficient design for the strength requirements when using aluminum.
What counts as 'flush' is a subjective measure which no one else can tell you if it is met. Are you going to run with more aggressive camber? How much stretch is acceptable on a tire? How low will your car be?
Split 5 spoke like this (minus the lightening pockets and specific rim/concavity) are pretty common because it's effectively been mathed out as the most material efficient design for the strength requirements when using aluminum.
What counts as 'flush' is a subjective measure which no one else can tell you if it is met. Are you going to run with more aggressive camber? How much stretch is acceptable on a tire? How low will your car be?
Heres my current track set 18s. 9.5 fronts with 255/35/18s and 11 rears with 295/30/18s. It gives a bit of an odd look, 1" lower and 1" more gap at the top, but I wont be using it on street. I can currently get my jack and quick jacks under in this setup but it may get tight with coil overs dropping another 10mm. If it proves to be a PITA I can switch to a 40/35 setup.
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- Thread starter
- #40
my decision I think was when I looked at suitable 200TW tires. I found there was a much better selection in the stock width. Otherwise, I would have leaned towards GT4 width
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