Downgrading from 20" to 19" on GTPE for ride quality improvements

[markboris]

Great insights from everyone—thanks for all the input so far!

I’m about to pull the trigger on some new wheels. My main concern is the small bumps and harsh impacts, which have been a bit of an issue. The bounciness does improve in Engage and Unbridled modes, so I’m hopeful that the combination of larger sidewalls and lighter wheels will help smooth things out even more. I am also looking into the sway bars and bushing option, but still trying to determine the best product for the GTPE.

Now, I’m just finalizing my decision on wheel and tire fitment. The stock setup is 245/45R20, giving me 4.3 inches of sidewall and a 28.7-inch diameter.

I’m considering switching to 19x8-inch wheels paired with one of the following:

• 235/55R19 tires: Increases to 5.1-inch sidewall and a 29.2-inch overall diameter (1.7% increase)
• 245/55R19 tires: Increases to 5.3-inch sidewall and a 29.6-inch overall diameter (3.1% increase)

I’m leaning toward the 245 width to maintain the same width as stock and take advantage of the even taller sidewall. However, does anyone know if a 3.1% diameter increase might be too large and potentially cause issues like rubbing or affect the suspension?

For tires, I’m thinking of sticking with the Pirelli Scorpion AS Plus 3 that I currently have, as it seems to perform well overall. But I’m open to other suggestions if anyone has had success with something else.

Looking forward to any thoughts or feedback before I make the leap!

Thanks again!

Hey Dan, going with 19" wheels on a GTPE can be challenging since many will not fit as the back of the wheel comes too close to the brake caliper. The OEM 19" Premium wheels fit but just barely. It all depends on the design of the wheel itself.

I know you're looking for a taller sidewall but the 245/55 is just over a 3% difference in diameter than stock and you are supposed to stay below 3%. Has nothing to do with fitment. The issue is the drive system. Not sure how the safety features will react.

Those Pirelli's are one of the smoothest riding grand touring all season tires you will find. I would stick with those if that is your goal.

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[tuminatr]

It's true about the wheels many designs will hit the calipers. Make sure you test fit whatever you buy before mounting tires on the wheels as most wheels are not returnable if tires have been mounted on them.

I would stick to the same overall height as the factory tires the 245/45/20 is 28.68" tall a 245/50/19 is 28.65" tall. With he 245/50/19 you add about .5" of sidewall. The 245/50/19 105 XL is also a higher load rating and you can safely lower the tire pressure to 37 PSI to get a smoother ride.

As for tires I did a set of Quatrac Pro+ in 245/50/19 105v XL they are efficient and provided a smooth quiet ride. Also considerably better in the wet and are rated to be better in the snow. The Pirellis you mentioned have good test results too.

 

[danperson1]

I haven't made any changes yet, however recently the temperature dropped and my tire pressure came down to 31 psi. I've noticed my complaints with the ride are almost gone. It rides really nice now, still taut but much smoother overall.

I don't think this is a safe PSI for the weight of the car so I'm going to put it back up to at least the 35 range. The fact the lower tire pressure makes such a difference gives me more confidence downsizing the wheel size can give me what I'm looking for.

 

[tuminatr]

I haven't made any changes yet, however recently the temperature dropped and my tire pressure came down to 31 psi. I've noticed my complaints with the ride are almost gone. It rides really nice now, still taught but much smoother overall.

I don't think this is a safe PSI for the weight of the car so I'm going to put it back up to at least the 35 range. The fact the lower tire pressure makes such a difference gives me more confidence downsizing the wheel size can give me what I'm looking for.

Tire pressure makes a huge difference. Many forum members have gone to a 255/45/20 105. The higher load range supports the same weight at a lower 36 psi.

It certainly would be cheaper to keep the same wheels and make ride quality better. Also when looking at tires pick something In the grand touring category as that tends to prioritize ride quality.

I just installed my Quatrac Pro+ and took off UHP summer tires. The grand touring QTP+ is so much more plush

 

[Mach1E]

I haven't made any changes yet, however recently the temperature dropped and my tire pressure came down to 31 psi. I've noticed my complaints with the ride are almost gone. It rides really nice now, still taut but much smoother overall.

I don't think this is a safe PSI for the weight of the car so I'm going to put it back up to at least the 35 range. The fact the lower tire pressure makes such a difference gives me more confidence downsizing the wheel size can give me what I'm looking for.

This is what you said a few months ago-

“I’ve already tried lowering the tire pressure from 39 to 35 PSI, but it didn’t make much difference, “

 

[danperson1]

This is what you said a few months ago-

“I’ve already tried lowering the tire pressure from 39 to 35 PSI, but it didn’t make much difference, “

Going from 35 to 30 was a lot more noticable for some reason. Sitting at 33 right now and it's a decent compromise.

 

[Mach1E]

Going from 35 to 30 was a lot more noticable for some reason. Sitting at 33 right now and it's a decent compromise.

Then you may be happy going with 255 tires that you can safely ride at lower pressure.

Would be cheaper than buying new wheels and look better too.

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