Downsizing wheels?

[mattbostonmache]

If I get the premium with 19" wheels, can you get a set of 18" wheels (like the ones on the select) and get tires with a taller sidewall to maintain the same radius and circumference? (to be more forgiving of pothole and rough surfaces?

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[generaltso]

Yes. 225/60R18 will be very close in circumference. About .2 mph difference at 70mph.

 

[JBA]

If I get the premium with 19" wheels, can you get a set of 18" wheels (like the ones on the select) and get tires with a taller sidewall to maintain the same radius and circumference? (to be more forgiving of pothole and rough surfaces?

Higher tires will help off course but I fear that the investment and obvious downgrade in looks isn't worth the little extra comfort. The biggest issues is in the springs itself and the (very) high recommended PSI. Basically you are only adjusting 1 of the 3 issues.

I'm going from select 18inch to 20inch and will expect less comfort from it but so be it. However for 20inch 245's Ford recommends a considerable lower PSI than the 225's 18 and 19 inch. I wouldn't be amazed if the comfort would be all the same due to it.

I tend to believe that it all has to do with the car being heavy and in corners higher and smaller tire sizes are much more sensitive to weight transitions in corners hence the higher required PSI compared to lower and wider sized tires.

No expert though so could be wrong

 

[tuminatr]

Changing wheel/tire size is a bit of a balancing act. Your idea that the larger sidewall will help with potholes has merit, but so does a 245/45/20 run at 36psi may actually offer a smoother and less bouncy ride than the 18" or 19" combo. Although lower PSI may hurt efficiency / rolling resistance.

Other factors can have an effect like the weight of the wheel/tire combo. A light wheel tire combo will accelerate faster and take less energy to get up to speed. Lightweight wheel tire combo ideal for road force driving and city driving. However, at highway speeds, a lighter wheel/tire combo may use more energy. I read there is a debate on the science of this so it would be fun to experiment.

I would say try what you want and post your results

 

[tman]

If I get the premium with 19" wheels, can you get a set of 18" wheels (like the ones on the select) and get tires with a taller sidewall to maintain the same radius and circumference? (to be more forgiving of pothole and rough surfaces?

I have had this thought too. I am working on ordering a GT, but I'd really prefer an 18" wheel. I bet trading those 20" GT wheels to somebody won't be too tough....

 

[JBA]

I have had this thought too. I am working on ordering a GT, but I'd really prefer an 18" wheel. I bet trading those 20" GT wheels to somebody won't be too tough....

For sure you won't have any issue and I bet you'll even get a nice extra $ on top but why buy a GT with all the HP, Tork and looks and destroy it all with the 18"? The looks are a personal thing but you won't be able to use half of the tork and hp on a GT with the 225's 18inch. Even an RWD SR is understeering in each corner if it's only a little wet.

 

[tman]

For sure you won't have any issue and I bet you'll even get a nice extra $ on top but why buy a GT with all the HP, Tork and looks and destroy it all with the 18"? The looks are a personal thing but you won't be able to use half of the tork and hp on a GT with the 225's 18inch. Even an RWD SR is understeering in each corner if it's only a little wet.

I’m no expert on wheels and tires, but my thinking is that
A) the 18” is better for EV range than 20”
B) no reason an 18” wheel can’t still be wide and grippy - be reason I have to get the wheels from a MME Select.

and I’m not crazy about the GT wheels in the first place.

 

[mattbostonmache]

I thought in the Roadshow video about the GT that they mentioned that the GT had bigger disc brakes (rotors and calipers).

That might cause an issue if you try to downsize.

I'm not sure of that was the GT Performance only or both GT variants.

I'm not sure where you'd go to look at the brake specs. I didn't see that on the dealer spec sheet.

 

[JBA]

I thought in the Roadshow video about the GT that they mentioned that the GT had bigger disc brakes (rotors and calipers).

That might cause an issue if you try to downsize.

I'm not sure of that was the GT Performance only or both GT variants.

I'm not sure where you'd go to look at the brake specs. I didn't see that on the dealer spec sheet.

You are actually right, they are fitted with brembo brakes with 19inch disks (taken from Frod ford spec: Ventilated disc 19"/4 piston fixed ) . Bit strange but the all other models have 18"/4 piston fixed which would never fit 18 inch wheel so i guess it's including the diskbrake. Nevertheless, 19inch will be bare minimum for GT if not 20inch.

I’m no expert on wheels and tires, but my thinking is that
A) the 18” is better for EV range than 20”
B) no reason an 18” wheel can’t still be wide and grippy - be reason I have to get the wheels from a MME Select.

and I’m not crazy about the GT wheels in the first place.

A) is indeed a fact (roughly 5%)
B) 18inch can be grippy enough if you would fit wider tires however that requires 8J or higher. The specific select wheels you mention are are 7J and 225's are already above recommended width. 225 is mentioned as maximum width according to several rim suppliers. Both 18inch as 19inch with 7J and 225 really look ballonish (18inch most) due to the rims being "so small" compared to the tires. You really can't and should go any wider on those.

Also note that 18inch and 19inch 225 wheels are recommended by for to be inflated 20% harder than the 20inch 245 wheels of the GT. This will cancel out the difference in size for most part already. Also the GT has magnetic suspensions which will make the ride even more smooth.

 

[mr_raider]

Are 17" wheels possible or does that create brake clearance problems?

 

[generaltso]

Are 17" wheels possible or does that create brake clearance problems?

I don‘t think so. The 18”s are already really close.

 

[harrysiii]

You are actually right, they are fitted with brembo brakes with 19inch disks (taken from Frod ford spec: Ventilated disc 19"/4 piston fixed ) . Bit strange but the all other models have 18"/4 piston fixed which would never fit 18 inch wheel so i guess it's including the diskbrake. Nevertheless, 19inch will be bare minimum for GT if not 20inch.




A) is indeed a fact (roughly 5%)
B) 18inch can be grippy enough if you would fit wider tires however that requires 8J or higher. The specific select wheels you mention are are 7J and 225's are already above recommended width. 225 is mentioned as maximum width according to several rim suppliers. Both 18inch as 19inch with 7J and 225 really look ballonish (18inch most) due to the rims being "so small" compared to the tires. You really can't and should go any wider on those.

Also note that 18inch and 19inch 225 wheels are recommended by for to be inflated 20% harder than the 20inch 245 wheels of the GT. This will cancel out the difference in size for most part already. Also the GT has magnetic suspensions which will make the ride even more smooth.

The GT actually has 15.1" rotors. The 19" was a typo and misinformation.

 

[Carsinmyblood]

Is the short sidewall hight partly due to the lateral forces that the front tires are subjected to?

I'd love to but more cushion om the road, but not if the sidewall curls under and scrubs and/or if the bead pops.

I've rolled the sidewall on a car and had the bead collapse. It's rather jarring. In a car as heavy as the MME, hard cornering has to be a concern.

 

[SirronD]

This is an older video, and is specifically about the Tesla Model 3 Performance, but the info on changing tire/rim sizes could be very relevant here.

Engineering Explained Video

 

[Carsinmyblood]

This is an older video, and is specifically about the Tesla Model 3 Performance, but the info on changing tire/rim sizes could be very relevant here.

Engineering Explained Video

That was interesting.

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