I'm thinking about changing my 19" Propeller Wheels for 20" Cyclones. Does anyone know if I can simply remove the current wheels and put the new ones on, or do other adjustments need to be made first? I'm thinking if it's simply a case of switching the wheels over I can do that myself. Otherwise it's off to the garage for me.

 

Yes - a simple swap.

Both Foosh and I switched from 18" to 20" wheels after buying our cars.

HTH

 

Yes you can, provided you keep the overall tire circumference the same. For instance, I also swapped from 18 to 20 inch wheels, but the tires changed in diameter and profile as well. On the 18's, the OEM front tires are 245/45/18, whereas they are 255/35/20 on the 20 inch wheels. Thus the tire sidewall decrease matches the wheel diameter increase keeping the same overall tire circumference. If you don't do this, the speed will be measured incorrectly, and I suspect other issues could arise with the anti-lock brakes for instance.

 

+1 to no complications at all.

As an interesting side-note, when I changed my OEM 18" wheels and tires to OEM 20" wheels and tires in my garage, I placed both the front and back 18s, on top of the front and back 20s. The 20s were almost 1" taller in diameter. I also have more ground clearance on the 20s than I had on the 18s.

However, and most importantly, the speedometer accuracy (verified by GPS) did not change at all. In fact, my speedometer always reads exactly the same speed as my smart-phone measured speed using the Waze nav app.

That leads me to suspect that the speedometer is fed by the car's GPS.

 

How much did the ride quality decrease after the switch?

 

Foosh, you made me think twice. I had assumed that the OEM tire/wheel combinations were identical in circumference, but hadn't verified it. So I went onto TireRack and checked. The 18 inch tires in Michelin PSS are listed as 26.7" circumference (780 revolutions/mile), and the 20" tires are 27" circumference (770 revolutions/mile). So at 60 mi/hr, the sensor would record 13 revolutions /second on the 18's and 12.833 for the 20's. That's slightly more than a 1% difference, certainly within the margin of error for typical engineering tolerances. Thus I'm not surprised that you see no difference in GPS measured speed.

For those that are leasing, however, switching to 20's will give them 300 "bonus" miles on a 30000 mile lease.

 

In switching from 19" to 20", I could perceive no change in ride quality.

 

That may be true with the PSS, which I do not have, and I was talking about the OEM PZeros in 18 and 20 OEM sizes. I trust my actual measurements more than I would trust whatever specs Tire Rack publishes. In this case, as I said, the difference was nearly 1".

It is well established that tire sizes vary significantly between manufacturers.

On ride quality, I perceive the 20s as slightly harsher than the 18s, but for me that's offset by the feeling that the car is significantly more planted with a crisper turn-in. I'm sure the difference is less significant going from 19 to 20.

 

With the non-dynamic suspension the ride was - in some respects - better.

Which was odd. I was left thinking that the spring and damping rates had been set using the larger wheels.

On the smaller wheels it seemed the suspension needed two goes to absorb a bump. As if the sidewall deflected first, followed by the spring and damper, then the sidewall bounced back leaving the spring and damper confused. Or at least, that's how it felt.

On the larger wheels it felt like the spring and damper and the tyre were moving together.

Maybe there was a point to those lectures many years ago about Simple Harmonic Motion, Resonance and damping...

 

Yeah...like I can remember much from those lectures over four decades ago.

 

I would guess the unsprung weight is greater for the 20" wheels? That must affect something...

 

Ok, folks ... I've got my 20" wheels and am going to fit them at the weekend.

The new wheels include tyre pressure sensors. Does anyone know if my 2014MY F-Type will automatically detect them or if I need to take it to the dealership to get them wired up? Does the base model even support tyre pressure sensors?

 

During the '14 production run, JLR changed TPMS sensor frequencies, so depending upon when your car was built, it may not communicate with the sensors in your new wheels. However, you'll know immediately because the car will automatically detect the compatible sensors.

Worst case is you'll have to swap them out. Before you mount them, you can ask a dealer to check which sensors you should have by asking them to run the VIN. My car was set-up for the old sensors, and my tire and wheel vendor installed them before shipping.

Don't know what the regulations require in the UK, but all US cars must have TPMS.

 

NOT a legal requirement in the UK