Wheel noob - 19" / 18" performance change questions -

[krees]

I just swapped my 20s for 18s with a 18x245x40 michelin pilot sport as/3+ and its much more comfortable. I no longer pucker around choppy roadways. I havent really pushed too hard yet so cant say for torque steer but i can drive in sport or r+ confidently now and i love that!

Wish i had done it sooner.

Sponsored

 

[NapalmEnema]

I am usually parked out around Westheimer & Montrose. I commute in from Sugar Land. It's a great 22-mile drive on the freeway, but the local streets are less than smooth.

Ah gotcha, I live around where you work and commute downtown where I see that other R similar to yours.

Well when the world stops ending we can grab lunch lol

 

[NKOTB]

Hello,

I'm running the 19" Motegi MR924's with Michelin PS4S in 245/35R19. I haven't been able find any posts about daily driving air pressures. Any consensus on cold pressure(s)? Same front & rear? FWIW, I'm in ATL, so summer cold vs winter cold pressure(s) are of interest too?

Thanks for your advice!

 

[tinyman392]

Hello,

I'm running the 19" Motegi MR924's with Michelin PS4S in 245/35R19. I haven't been able find any posts about daily driving air pressures. Any consensus on cold pressure(s)? Same front & rear? FWIW, I'm in ATL, so summer cold vs winter cold pressure(s) are of interest too?

Thanks for your advice!

Look in your door jam, they‘re posted in there. I believe it’s 35 front and 33 rear. The owners manual may or may not have suggestions if you’re doing performance driving as well (I don’t remember off the top of my head on that one though).

 

[NKOTB]

Look in your door jam, they‘re posted in there. I believe it’s 35 front and 33 rear. The owners manual may or may not have suggestions if you’re doing performance driving as well (I don’t remember off the top of my head on that one though).

Thanks! Let me clarify my question a bit more. Correct, understood on door jamb 35/33 recommendations, however they are for a different size, compound and sidewall stiffness tire, so just wondering if they are still optimal?

FWIW, I found a few PS4S related postings on the Porsche forums about running lower than mfg. recommended pressures with better wear and performance.

So I'll surely stick with the 35/33 for now, but if anyone else is seeing poor wear from this, or if you're seeing benefits from running something different, I'd love to hear your experience.

Thanks again.

 

[ayau]

Thanks! Let me clarify my question a bit more. Correct, understood on door jamb 35/33 recommendations, however they are for a different size, compound and sidewall stiffness tire, so just wondering if they are still optimal?

FWIW, I found a few PS4S related postings on the Porsche forums about running lower than mfg. recommended pressures with better wear and performance.

So I'll surely stick with the 35/33 for now, but if anyone else is seeing poor wear from this, or if you're seeing benefits from running something different, I'd love to hear your experience.

Thanks again.

There's no optimal psi for every situation.

For example, at the track, you'll start at around 30psi cold, do a lap or 2, pit out, look at sidewall wear, increase/decrease pressure based on wear. Usually you'll end up being around 35-40psi hot.

For daily driving, you can run lower psi for more 'grip', but how often are you taking hard corners at 45mph+? You'll just end up with lower mpgs and probably wear out the tread.

The door jam psi is the recommended overall psi for street use. It'll usually work for 95% of the population.

 

[Lust]

What characteristics of the 20” do you like? We can start there and recommend alternatives based on your preference

 

[NapalmEnema]

What characteristics of the 20” do you like? We can start there and recommend alternatives based on your preference

In order to entertain a 19 or 18" I would be wanting the same feel and handling as the 20" ideally. Sounds like that's not viable though so sticking with the 20's for now.

 

[ayau]

You’ll gain the most performance by going with a lighter 19 or 18 wheel. Saving 5-8lbs per corner is pretty significant. There’s literally no downside by going with a lighter wheel assuming it’s not a cheap Chinese wheel that doesn’t meet crash safety standards.

To reduce torque steer, you can stick with a 19x8.5 +53 wheel. OEM is +60. This should pretty much give you 0 torque steer.

To get immediate steering response, most performance max summer tires should have pretty stiff sidewalls. If you want even more stiffness, bump the tires 2-6 psi above OEM psi specs. This will stiffen the sidewalls further.

I can’t think of an objective reason to stick with the OEM wheels.

 

[Lust]

In order to entertain a 19 or 18" I would be wanting the same feel and handling as the 20" ideally. Sounds like that's not viable though so sticking with the 20's for now.

One could argue that going to a small diameter wheel would improve handling so you might want to be more specific as to what trait you’re looking for. I think the only good trait about the 20s would be more direct feel. Though you gain a bunch of unsprung mass with 20s. With 18s you get a lighter wheel with a bunch of tire options. If you get a nice 200tw with stuff sidewall, it’ll feel similar to the 20s but not as direct. The trade off would be the grip available would increase especially if you go wider. This is pretty much why all of the track guys are on 18s

 

[NapalmEnema]

One could argue that going to a small diameter wheel would improve handling so you might want to be more specific as to what trait you’re looking for. I think the only good trait about the 20s would be more direct feel. Though you gain a bunch of unsprung mass with 20s. With 18s you get a lighter wheel with a bunch of tire options. If you get a nice 200tw with stuff sidewall, it’ll feel similar to the 20s but not as direct. The trade off would be the grip available would increase especially if you go wider. This is pretty much why all of the track guys are on 18s

Hmm interesting... I just love the car as it sits you know? So I worry that I put in a grand or so and don't like what comes out the other end. So a bit of a conundrum.

I think if I got some wheel time with a Type R and 18"'s or 19's I could better understand what changes - tough to do but it's hard to articulate what exactly changes, though most seem to think it does lessen the handling going smaller?

If 18's and 19's were optimal why did they go for the 20's, was it strictly looks? It feels like the smaller sidewall and stiffer due to that certainly is at play. I definitely don't like a rubber band feeling to handling where the sidewall flexes and snaps the car around, so am always looking to avoid that 'feeling'.

Thanks for the input

 

[Lust]

Hmm interesting... I just love the car as it sits you know? So I worry that I put in a grand or so and don't like what comes out the other end. So a bit of a conundrum.

I think if I got some wheel time with a Type R and 18"'s or 19's I could better understand what changes - tough to do but it's hard to articulate what exactly changes, though most seem to think it does lessen the handling going smaller?

If 18's and 19's were optimal why did they go for the 20's, was it strictly looks? It feels like the smaller sidewall and stiffer due to that certainly is at play. I definitely don't like a rubber band feeling to handling where the sidewall flexes and snaps the car around, so am always looking to avoid that 'feeling'.

Thanks for the input

I don’t know the exact reason for factory 20s tbh. Maybe it helped them at the ring achieve that specific time? I’m not sure. Looks can definitely be a part of it too.

I think 18s are the superior choice since you gain a thicker sidewall and more tire selection. I wouldn’t consider running a 20” ever

 

[ayau]

Hmm interesting... I just love the car as it sits you know? So I worry that I put in a grand or so and don't like what comes out the other end. So a bit of a conundrum.

I think if I got some wheel time with a Type R and 18"'s or 19's I could better understand what changes - tough to do but it's hard to articulate what exactly changes, though most seem to think it does lessen the handling going smaller?

If 18's and 19's were optimal why did they go for the 20's, was it strictly looks? It feels like the smaller sidewall and stiffer due to that certainly is at play. I definitely don't like a rubber band feeling to handling where the sidewall flexes and snaps the car around, so am always looking to avoid that 'feeling'.

Thanks for the input

I think you’re over thinking this. Your car isn’t going to handle like absolute garbage if you put 18/19. If you’ve never pushed your car to the limit, I doubt you’ll even feel the difference.

The thin OEM sidewalls essentially just gives you sidewall stiffness. Run a higher psi and you’ll essentially get the same effect. Summer extreme performance tire will also have stiffer sidewalls, but those aren’t for daily driving. The OEM Contis Honda are max performance summer, which have softer sidewall, all else equal.

The weight savings will far outweigh any negatives. Not to mention 18 tires are much cheaper than 20s.

Probably for marketing and aesthetic reasons to choose 20. 18s look a bit small in relation to the overall size of the car

 

[Shred]

Here's a video explaining the suspension geometry. It also explains the difference between torque steer and understeer. No matter what offset you have, a FWD platform will tend to have understeer. I know this helped me understand this car better, hopefully it helps others.

 

[NapalmEnema]

I think you’re over thinking this. Your car isn’t going to handle like absolute garbage if you put 18/19. If you’ve never pushed your car to the limit, I doubt you’ll even feel the difference.

The thin OEM sidewalls essentially just gives you sidewall stiffness. Run a higher psi and you’ll essentially get the same effect. Summer extreme performance tire will also have stiffer sidewalls, but those aren’t for daily driving. The OEM Contis Honda are max performance summer, which have softer sidewall, all else equal.

The weight savings will far outweigh any negatives. Not to mention 18 tires are much cheaper than 20s.

Probably for marketing and aesthetic reasons to choose 20. 18s look a bit small in relation to the overall size of the car

With respect bud, I do push my car and hard, so I don't want that 'at the limit' feeling to become something disagreeable to me. What I have read about the 18's is it re-introduces a lot of torque steer which is also undesirable to me at least since this car is so fun with the way it pulls straight presently.

Sponsored