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Discussion Starter · #1 ·
I'll be buying an Ascent soon, most likely the Limited, but I am apprehensive about the 20" wheels due to the increased risk of getting a flat tire that I have heard about. So I am debating between getting OEM 18" wheels installed on it instead, or maybe keeping the 20" wheels and buying "better" tires to reduce the risk of getting a flat.

Would installing a tire like the Goodyear Eagle Sport on the 20" wheels (which has a higher load rating and stronger sidewall) reduce the chances of getting a flat? Can anyone recommend a "better" tire than this for the 20" wheels, if the goal is to maintain good all-season performance but reduce the risk of a flat?

Or would I be better off getting 18" wheels instead? Are there any drawbacks to getting 18" wheels and simply selling or getting rid of the 20" wheels?

Also, in case anyone is trying to make a similar choice, I test drove Ascents with both 18" and 20" wheels. In urban driving the difference in feel, sound, and comfort between them is minimal. However, on the interstate, the 20" wheels had more noise, vibrations, and resonance, especially when driving over gaps and small potholes. This isn't a big enough reason by itself for me to buy the 18" wheels, but it is a noticeable difference...
 

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My previous vehicle has 20" wheels and I never had a flat over seven years outside of one nail in the tread. Clearly, the wheel didn't contribute to that. Yes, the lower profile tires used with the 20" wheels can be more easily damage if you routinely hit rough/sharp curbs, but otherwise, wheel size is more of a personal preference. Replacing the 20" wheels with 18" wheels will also cost you money so it has to actually be something you want to do.
 

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Discussion Starter · #4 ·
It's nice to hear that you made it 7 years with only one flat due to a nail. Maybe the 20" wheels aren't so bad. Unfortunately, we have tons of potholes here, and they sometimes difficult to avoid due to traffic conditions.

Swapping might be an option, but since the nearest dealer is ~2 hours away, there aren't many other Ascents near me.
 

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I live in Pennsyltucky...we know potholes. :) :D
 

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18" wheels gives you a lot more options, especially for bad weather travel, off-roading, etc - while retaining stock circumference and width.
 

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While I am not a driving "connoisseur", the drive with 18" wheels is different.

I have 18" winter wheels and stock 20" (Touring) for non-winter wheels.

I feel that stock wheels provide sharper handling and feel of the road, while 18" cushion more road (which is an intend for winter driving). I like summer driving on stock 20"
 

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Discussion Starter · #8 ·
Thanks for the helpful comments. Do you think that installing 18" wheels on a Limited Ascent would have any negative effects? Basically I'm wondering if Ascents that come from the factory with 20" wheels are built or tuned differently than Ascents that come with 18" wheels.

One reason I ask is because page 64 of the Ascent owner's manual says that "installation of a tire of different size and construction from the tires specified on the vehicle placard attached to the driver's door pillar or specified for individual vehicle models in this Owner's Manual" can interfere with proper operation of the seat belt pretensioners.

I'm probably overthinking this, but any feedback or thoughts would be helpful...
 

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You can use either wheel size.
 

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Thanks for the helpful comments. Do you think that installing 18" wheels on a Limited Ascent would have any negative effects? Basically I'm wondering if Ascents that come from the factory with 20" wheels are built or tuned differently than Ascents that come with 18" wheels.

One reason I ask is because page 64 of the Ascent owner's manual says that "installation of a tire of different size and construction from the tires specified on the vehicle placard attached to the driver's door pillar or specified for individual vehicle models in this Owner's Manual" can interfere with proper operation of the seat belt pretensioners.

I'm probably overthinking this, but any feedback or thoughts would be helpful...

All you need to do is match the stock 18" Premium size, *AND* match the Premium 18" inflation (35psi instead of your current 33psi).

It's an accepted size, since the outer dimensions of the 18s and 20s is identical.

18"
Tire size: 245/60R18 105H @ 35psi
Wheel size: 18 x 7½ J
Inset: 55 (2.17)
P.C.D.: 114.3 (4.5)
682 revolutions per mile


20"
Tire size: 245/50R20 102H @ 33psi
Wheel size: 20 x 7½ J
Inset: 55 (2.17)
P.C.D.: 114.3 (4.5)
681 revolutions per mile
 

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Discussion Starter · #11 ·
That's great info, thanks. I assume the TPMS would still work? Would they need to transplant the sensors to the new wheels, or would the new wheels come with sensors? Sorry, maybe this is a silly question, I'm just trying to think it all through.
 

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That's great info, thanks. I assume the TPMS would still work? Would they need to transplant the sensors to the new wheels, or would the new wheels come with sensors? Sorry, maybe this is a silly question, I'm just trying to think it all through.
You need new sensors. There's a thread with all the info you need to know.
 

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As mentioned, you can drop down to 18-inch wheels and tires without issue just bear in mind that you may notice a slight change in handling.

Lower profile tires (like you're O.E. tires) tend to respond quicker due to the shorter sidewall height whereas a taller profile tire has more "cushion" so to speak that takes a little longer to responded. In reality though, the average drier will likely not notice this but will likely pick up on the improved comfort (again due to sidewall height).

To touch on the TPMS sensors, you can swap over the factory sensors into the new wheels or purchase a new set - whatever works best for you!
 

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Discussion Starter · #14 ·
As mentioned, you can drop down to 18-inch wheels and tires without issue just bear in mind that you may notice a slight change in handling.

Lower profile tires (like you're O.E. tires) tend to respond quicker due to the shorter sidewall height whereas a taller profile tire has more "cushion" so to speak that takes a little longer to responded. In reality though, the average drier will likely not notice this but will likely pick up on the improved comfort (again due to sidewall height).

To touch on the TPMS sensors, you can swap over the factory sensors into the new wheels or purchase a new set - whatever works best for you!
Awesome, thanks. Do you have a sense for how much more likely it is to get a flat tire with the 20" wheels (with tires that have less sidewall) than the 18" wheels (with more sidewall)? This is my main reason for considering the switch. I'm wondering if the expense of getting 18" wheels is justified for this reason, or if the increased risk could be reduced in a less expensive way (e.g. buying better tires for the 20" wheels).
 

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The only increased risk of getting flats with 20" vs 18" is if you hit a large/sharp bump hard enough to cause a blowout of the sidewall. The taller sidewall of the 18" can cushion it more.

So unless you bump into large curbs or have killer potholes or go offroading you should be fine.
 

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Awesome, thanks. Do you have a sense for how much more likely it is to get a flat tire with the 20" wheels (with tires that have less sidewall) than the 18" wheels (with more sidewall)? This is my main reason for considering the switch. I'm wondering if the expense of getting 18" wheels is justified for this reason, or if the increased risk could be reduced in a less expensive way (e.g. buying better tires for the 20" wheels).
I don't have any hard data to share on that subject but it ultimately it depends on the terrain and roads you drive.

If the roads are properly maintained you may never have an issue with the lower profile tires but if the roads are pothole strewn the probability of damaging a lower profile tire is greater than a tire with more sidewall. The same can be said for off-road conditions/trails that are rutted or very rocky.

To touch on expenses, initially 18-inch wheels and tires cost more but replacement 18" tires typically run less than tires of equal size in 20-inch so eventually the wheels would pay for themselves.
 

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I went with 18”. 20” gives you no more clearance so you have less tire thickness. Most likely impacts ride, responsiveness. Before I bought I was looking for a full size spare on Ebay and found all sorts of 20” sets but no 18”. I suspect folks might be swapping the 20” for 18” but don’t know for sure. Just a guess. I mount the full size spare on a Wilco Swing-away. If you are a city only driver I think the 20”’would be fine.
 

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Discussion Starter · #18 ·
I picked up my new Ascent Limited yesterday. For what it's worth, I decided to stick with the 20" wheels for a few months and see how things go. During the final inspection I did notice that the tire pressures were all high, at around 40 to 42 psi. I let some air out to bring them down to the recommended level. After that, they seemed quieter on the highway (the "ping" noise followed by ringing vibrations that previously occurred over small gaps in the interstate seemed to be a lot quieter, not really an issue anymore) but maybe that's all in my head.
 

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I think 33 PSI on 20” is redaction for comfort …
Normally most manufactures (including Subaru ) increase PSI with bigger wheel or keep it same
For me Out of 18+ cars Ascent is the first one to have lower PSI for bigger wheels
 

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I've noted quite a few instances where the dealer prep team (regardless of brand) will forget to check and adjust tire pressures after delivery. Manufacturers tend to ship them "pumped up" hard, but the psi listed on the door frame is where they need to be as a starting point for the new owner. Many of us will adjust slightly from there based on personal preferences, of course.
 
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