BajaNomad - 18 inch vs 20 inch rims

18 inch vs 20 inch rims

JZ - 9-18-2019 at 09:04 PM

Lifting the truck up a bit - 3-4 inches. Putting 35 inch tires on it.

How much of an offroad performance / comfort difference is there between 18 and 20 inch rims?

[Edited on 9-19-2019 by JZ]

BajaParrothead - 9-18-2019 at 09:09 PM

I just switched from 17 to 20 with 12.5 X 35 and I definitely feel more vibrations and hits than I did with the smaller wheel. The other thing you might consider, is a 33" on a 20" wheel doesn't leave you with much sidewall. Not much room to air down without compromising the rim for hits. Just my experience, but I wish I had not swapped to the 20's.
Not sure how much it matters, but my truck is a Dodge 2500 Cummins, so it's pretty heavy.

[Edited on 9-19-2019 by BajaParrothead]

4x4abc - 9-18-2019 at 09:12 PM

general rule for off-road - the smaller the wheel, the better (more volume of air)
general rule for on-road and off-road - the smaller the wheel, the more comfort (air acts as a spring)

general rule for on-road - bigger wheels are better for high speed performance
and they are eye catchers

18" on 33's are not good for off-road
more flats, less comfort, less flexibility for airing down, shorter side wall leds to more compression cuts

Bajazly - 9-18-2019 at 09:57 PM

If I did what you do JZ, and I do, I would stick with 17’s. Very common tire size and as others have said about comfort and airing down, all spot on. Also with 35’s you will probably want/need to regear as well, she’ll be a bit of a dog with the stock gears.

I got a set of TRD wheels for not much but next time I need tires I may go to 17’s just because how common they are and are a bit more economical too.

But if you are gonna go with 20’s, make sure they are spinners :bounce:

JZ - 9-18-2019 at 10:19 PM

Ok, thoughts on this tire dimension wise? How wide is too wide?

https://www.amazon.com/Nitto-Terra-Grappler-Traction-Radial/...

[Edited on 9-19-2019 by JZ]

Aesthetics v. Performance

MrBillM - 9-18-2019 at 10:25 PM

The only performance purpose for the move to larger relative diameter wheels was to accommodate larger brakes. Which outweighed the increase in unsprung weight and ride harshness.

Otherwise, it's simply an expression of (questionable) style.

Nikno - 9-18-2019 at 10:32 PM

I am running 20" rims with 35" tires on my Wrangler and that's the one thing I regret about my build. They look great but off road performance isn't as good. I can still get through just about anything, but there have been a few situations when I have aired down significantly and it just didn't leave a lot of room between the rim and the tire. Also it's not as smooth off road. Someday when I have an extra 3 grand laying around I will get a set of 17" rims with 35s.

I have an older Jeep that's running 37" tires on 17" rims and I can easily air that thing down to 12 psi if I'm really in the chit. With the 20" rims anything under 25 psi starts to get hairy going over rocks. The 35s on 20" definitely handle better on the pavement though.

18" rims aren't as common and you might have trouble finding tires for it, especially in Baja.

JZ - 9-18-2019 at 10:44 PM

Quote: Originally posted by Nikno

I am running 20" rims with 35" tires on my Wrangler and that's the one thing I regret about my build. They look great but off road performance isn't as good. I can still get through just about anything, but there have been a few situations when I have aired down significantly and it just didn't leave a lot of room between the rim and the tire. Also it's not as smooth off road. Someday when I have an extra 3 grand laying around I will get a set of 17" rims with 35s.

I have an older Jeep that's running 37" tires on 17" rims and I can easily air that thing down to 12 psi if I'm really in the chit. With the 20" rims anything under 25 psi starts to get hairy going over rocks. The 35s on 20" definitely handle better on the pavement though.

18" rims aren't as common and you might have trouble finding tires for it, especially in Baja.

Thanks bud, appreciate your input.

Mulege Canuck - 9-19-2019 at 09:01 AM

Quote: Originally posted by Bajazly

If I did what you do JZ, and I do, I would stick with 17’s. Very common tire size and as others have said about comfort and airing down, all spot on. Also with 35’s you will probably want/need to regear as well, she’ll be a bit of a dog with the stock gears.

I got a set of TRD wheels for not much but next time I need tires I may go to 17’s just because how common they are and are a bit more economical too.

But if you are gonna go with 20’s, make sure they are spinners :bounce:

I thought about moving up from 17” rims, but like you say 17” are cheaper and more available. Easier for me when I have to chain up for snow. Other than sand, pizza cutters are better for traction.

Pacifico - 9-19-2019 at 06:31 PM

People have already nailed it, stick with 17" wheels. I have friends in the tire business and they all told me the same thing; run 17" wheels because tires are more readily available and cheaper than 18" and 20" tires. I run 35-12.50-17 tires which is very common and easy to find.

I run 37" tires on my pre-runner which I love, but not all trucks can accommodate that big of a tire. Even then, I still run a 17" wheel.

JZ - 9-19-2019 at 06:52 PM

Another question. I might be able to get 35's on my truck with just a leveling kit. I already have very good King shocks on it, so this would avoid replacing those.

The question is, do you need to lift the truck to get the the benefits of an upgraded UCA?

bajatrailrider - 9-19-2019 at 07:04 PM

No uca you don't need lift kit. Any large rim worst thing you can do if you drive off road. My toy prerunner 35/12.50/15 rides like a caddy. Dodge diesel 315/75/16. Nissan diesel 285/75/16. Would never run over 17in rims.

advrider - 9-19-2019 at 07:33 PM

Agree with what others have said. I just went from 16-18's with a leveling kit on my 04 chevy 2500. It won't see a lot of offroad so the 18's are OK and look good, no way I would go bigger. My scrambler run's 37's on 15 inch wheels and I will be going to 40's on 17's next because 15's are obsolete.
If I remember correctly you have a GMC or Chevy? If so checkout cognito out of Bakersfield' I just did a leveling kit from them' not cheap but very nice.

JZ - 9-19-2019 at 08:07 PM

There are more wheel choices for 18 vs. 17 for 3/4 ton Silverado's.

Tires as well I believe.

[Edited on 9-20-2019 by JZ]

advrider - 9-19-2019 at 08:11 PM

Correct, my buddy that owns a tire shop recommended the 18's for that reason. They are a few dollars more for tires but not enough to matter. Note, when truck is empty drop the pressure to about 40-45 PSI vs's 60 for a loaded truck, ride's much better..

JZ - 9-19-2019 at 08:19 PM

Quote: Originally posted by advrider

Correct, my buddy that owns a tire shop recommended the 18's for that reason. They are a few dollars more for tires but not enough to matter. Note, when truck is empty drop the pressure to about 40-45 PSI vs's 60 for a loaded truck, ride's much better..

Loaded is 70-75ish. Typically run 60-65 on the highway. In the dirt 35-40.

Bolt pattern and offset on the Silverado is making finding rims a b-tch.

Tire rim size choice

PaulW - 9-20-2019 at 09:06 AM

What size rim do you have now? it is a strong possibility that all you need is new tires and not tires and rims.
I have not checked all models, but the 17" would always be my choice for GM. Ram or Ford. They definitely work on Fords. More rubber between the rim and the ground is the goal for off road prowess and comfort ride. Big rims are highly regarded as BLING if that is your goal.
Driving off road with tall mims like 20"+ is a guarantee for bent rims.
Don't worry about availability for any size because there are to many tire companies that cater to all sizes.
I guess you know taller tires mean new gears to allow the truck to operate within its design.

My new Ford came with 18s and I and too cheap to switch to 17s. If I would switch to 17s I would try to keep the tire the same diameter to avoid new gearing.
=== === =

Quote: Originally posted by JZ

Lifting the truck up a bit - 3-4 inches. Putting 35 inch tires on it.

How much of an offroad performance / comfort difference is there between 18 and 20 inch rims?

[Edited on 9-19-2019 by JZ]

John Harper - 9-20-2019 at 09:29 AM

Quote: Originally posted by JZ

Bolt pattern and offset on the Silverado is making finding rims a b-tch.

Typical GM engineering. There's a brand new Colorado just down the street,
black paint is already peeling off the grill, still has paper plates!

And, keep an eye out for all the GM trucks with only one "daytime running light" because the other is burned out. Probably 60-70% of them.

John

AKgringo - 9-20-2019 at 09:49 AM

The clearance between the rim and the rocks only matters on the bottom of the tire, so there is only 1/2 inch difference between a 17, and an 18 inch rim!

About GM, I bought an older Isuzu recently, and found that the Isuzu V-6 is mated to a GM transmission. The same drivetrain is also used in the Honda Pilot.

BajaTed - 9-20-2019 at 12:25 PM

The tire contact patch is biggest on a 20" wheel, smallest on a 16"
Sidewall height is compromised on a twenty, greatest on a 16"
The unsprung weight of a 20" wheel is the highest, the lightest is a 16"

Right in the middle of 16 and 20 is 18.
Same size as this years F1 cars

BajaParrothead - 9-20-2019 at 12:42 PM

"My new Ford came with 18s and I and too cheap to switch to 17s. If I would switch to 17s I would try to keep the tire the same diameter to avoid new gearing."
=== === =

I found on my 2019 Ram that they went to a 20" wheel to accommodate the larger brake rotors and calipers. Even if I wanted to go down to a 16" or 17", I can't.

[Edited on 9-19-2019 by JZ][/rquote][/rquote]

mtgoat666 - 9-20-2019 at 01:17 PM

Quote: Originally posted by PaulW

My new Ford came with 18s and I and too cheap to switch to 17s. If I would switch to 17s I would try to keep the tire the same diameter to avoid new gearing.

when i bought my new F-150 a couple years ago, wheel size was an option, and I wanted 17" for better ride quality on rough roads and offroad, and was pleased that 17" was cheapest option of available wheels.

the trend of large rims on full size pickups is a fad that for shallow posers. if that fad of blingy wheels is your thing, why are you buying a pickup?

matthew_mangus - 10-4-2019 at 08:12 PM

I've learned over the years (often the hard way) that going big is for rookies and posers. I'm now trending the other way and going just large enough to get the job done. My primary rig ( I have 4 ) is running 285/75/17s and I'll likely downsize again to 70s the next time I buy tires.

I also have learned to be critical of tire / wheel sizes when other rigs are joining in on an adventure. A Range Rover sport w/ turbo on 20's w/ a Brembo big brake kit may be miles ahead of the convoy when on pavement, but then falls way behind and becomes a liability when we are aired down and he doesn't have enough sidewall to be able to float over the rocks. I have two friends who have been politely notified that they are no longer welcome on trips where we typically air down.

David K - 10-5-2019 at 08:17 AM

Quote: Originally posted by matthew_mangus

I've learned over the years (often the hard way) that going big is for rookies and posers. I'm now trending the other way and going just large enough to get the job done. My primary rig ( I have 4 ) is running 285/75/17s and I'll likely downsize again to 70s the next time I buy tires.

I also have learned to be critical of tire / wheel sizes when other rigs are joining in on an adventure. A Range Rover sport w/ turbo on 20's w/ a Brembo big brake kit may be miles ahead of the convoy when on pavement, but then falls way behind and becomes a liability when we are aired down and he doesn't have enough sidewall to be able to float over the rocks. I have two friends who have been politely notified that they are no longer welcome on trips where we typically air down.

Man, that's awesome! I would like to wheel with you!

AKgringo - 10-5-2019 at 09:48 AM

"My primary rig ( I have 4 ) is running 285/75/17s and I'll likely downsize again to 70s the next time I buy tires. "

My choice would be to stick with the 75 aspect, and lose some width. A 265/75 aired down should have plenty of surface area for flotation, and would be a better handling tire on the road, especially wet roads!

TMW - 10-5-2019 at 05:34 PM

My recently purchased 2006 Toyota 4Runner has 18 inch rims. I tried to put one of my 04 Tacoma 16 inch rim on and it was too small.It would go on but not rotate, locked against the rotor. In 2006 Toyota made three versions of the 4Runner two with 16 inch rims and the Limited with 18 inch. I haven't decide how much I'll do to it for off road That's why I have my Tacoma. I think I'll put rock slider on it and get rid of the goofy step board.

Ken Cooke - 10-5-2019 at 11:12 PM

I have 35"x12.5r15s on the little Jeep.
Currently, LT285 17's on the Jeep (Gladiator) truck.
Next size up for the Gladiator JT is either 37" or 38"
A 2". Daystar spacer lift is sitting in the garage :bounce:

Aftermarket 17x8" (beadlocks) wheels are part of the plan.

PaulW - 10-6-2019 at 05:46 AM

Check into using a spacer. It is a common solution to caliper to wheel interference. If you go that way be sure you do not cheap out. Buy a quality spacer. Your vehicle specific forums will guide you.

Quote: Originally posted by TMW

My recently purchased 2006 Toyota 4Runner has 18 inch rims. I tried to put one of my 04 Tacoma 16 inch rim on and it was too small.It would go on but not rotate, locked against the rotor. In 2006 Toyota made three versions of the 4Runner two with 16 inch rims and the Limited with 18 inch. I haven't decide how much I'll do to it for off road That's why I have my Tacoma. I think I'll put rock slider on it and get rid of the goofy step board.

TMW - 10-6-2019 at 11:07 AM

Thanks Paul, I never considered that.

matthew_mangus - 10-6-2019 at 10:54 PM

Quote: Originally posted by David K

Man, that's awesome! I would like to wheel with you!

Hmmm, I dunno. After your latest adventures in Raptors, we'd probably be pretty boring to you. :lol:

David K - 10-7-2019 at 09:47 AM

Nope, I respect your four-wheeling style. I love going to places in low range and where lockers or traction control gets you there safely with minimal body damage.
The road to Mission Santa María is a favorite trip of mine as it combines many things that make Baja special for me. Riding in a Raptor driven by Curt LeDuc or Cameron Steele is fun but not the way I normally drive in Baja (in my Off-Road TRD Tacoma 4x4).

matthew_mangus - 10-7-2019 at 07:18 PM

Quote: Originally posted by David K

Nope, I respect your four-wheeling style. I love going to places in low range and where lockers or traction control gets you there safely with minimal body damage.
The road to Mission Santa María is a favorite trip of mine as it combines many things that make Baja special for me. Riding in a Raptor driven by Curt LeDuc or Cameron Steele is fun but not the way I normally drive in Baja (in my Off-Road TRD Tacoma 4x4).

Right on. I'll have to coordinate an adventure with you some time.

Is the Mision de Santa Maria accessed via the dirt track that starts in the NW corner of the Ranch Santa Ynes airstrip? Also, do you reach the Oasis Santa Maria by following the same track until it eventually disssapears in the riverbed?

Doug/Vamonos - 10-13-2019 at 07:59 AM

My 05 F-250 has 18s. True, not a big choice of tires in that size rim. But I've settled on Nitto Trail Grappler M/Ts on LT285x75x18. I'd prefer 17s but have been too cheap to replace the wheels/tires and I like to look of the factory 18s. The 285s are pretty close to 35".

PaulW - 10-13-2019 at 09:17 AM

Doug. That tire is almost exactly a 34" diameter tire @ 592 rev/mile

David K - 10-13-2019 at 09:40 AM

Quote: Originally posted by matthew_mangus

Quote: Originally posted by David K

The road to the mission begins at the far left gate (as seen when driving to the ranch from Hwy. 1) from the old restaurant/ ranch of Santa Ynez... the opposite side from the airport. See it on Google Earth.

There are two oasis locations associated with Santa María, perhaps three:

a) The first palms you drive through, below the 'widowmaker' grade, about 1 mile before the mission.

b) The oasis we camped next to in 2007 is a mile past the mission and then back up the arroyo from the road. This is where the bighorn sheep visited us.

c) The "La Poza de Escuadra" as some have called it which is in the canyon maybe 3 miles beyond the mission... a long, steep hike is required to the end of the bulldozed road, then down into the canyon on the Indian Trail (El Camino Real before 1768, replaced by a new route on the north rim of the canyon). This is the oasis on my map...

Here are my last two trip webpages, to the mission. The 2007 one contains a road log:

2007: http://vivabaja.com/msm/
2010: http://vivabaja.com/msm2010/

ROAD LOG
0.0 Rancho Santa Ynez, take road through left gate, north of ranch.
0.9 FORK, go left/ uphill.
1.8 Deep Gully, 4WD climb out (if this scares you, go back!).
2.4 Rock pile, a road to left, go straight/ right fork.
4.7 Cement monument off to left (tracks continue past monument).
5.6 Arroyo crossing with palms.
9.9 Peninsular Divide, view of Punta Final on the gulf.
13.3 Top of the 'Widowmaker' grade.
14.4 MISION SANTA MARIA
15.4 Road enters sandy Arroyo Santa Maria, after very steep downgrade. (Bighorn oasis to the left)
15.7 Turn left, out of arroyo (may be hidden by plants). Tracks ahead in arroyo end in 1/4 mile.
15.9 El Camino Real climbs to the left, up hillside. The mission trail stays out of the canyon, along the north ridge and returns to the arroyo at the east end of the canyon.
16.0 Roadbed washed out. Park and hike on to end of bulldozed grade to see petroglyphs, canyon view, Indian trail to canyon bottom.

JZ - 10-13-2019 at 10:53 AM

Quote: Originally posted by PaulW

Doug. That tire is almost exactly a 34" diameter tire @ 592 rev/mile

It's almost 35. 34.83.

Doug/Vamonos - 10-13-2019 at 08:55 PM

Details, details. :-)

mtgoat666 - 10-13-2019 at 09:12 PM

Quote: Originally posted by JZ

Quote: Originally posted by PaulW

Doug. That tire is almost exactly a 34" diameter tire @ 592 rev/mile

It's almost 35. 34.83.

35.08”

JZ - 10-13-2019 at 09:19 PM

Quote: Originally posted by mtgoat666

35.08”

Your calculator is no bueno.

PaulW - 10-14-2019 at 07:50 AM

For those failing math education or forgetting how to do the math
Tire diameter = 63360/(pi*RPM)
Or 63360/(3.1416 * 592)=34.07”
Here is the derivation 5280(12)/Pi(RPM)=diameter in inches
Pi = 3.1416 and RPM is manufacturers rev per mile.
For better understanding go read
https://sciencing.com/calculate-tire-turns-per-mile-7797454....

What you get from various tables from the web just ignore because they are just approximations.

You might want to know that using the science and correct math when I adjusted my speedo via the ECU I used the math above and got exact MPH on my speedo. Math and science never fails.

[Edited on 10-14-2019 by PaulW]

mtgoat666 - 10-14-2019 at 08:19 AM

read the specs for the subject tire, on the mfg website, inflated dimensions...

advrider - 10-14-2019 at 08:25 AM

Ken, could we get some pic's and info on your new Gladiator? How are you liking it and what are your plans for it? I'm very interested in jeeps newest offering. You could probably start a new topic even?

PaulW - 10-14-2019 at 08:33 AM

Goat
The rev per mile is actual from the manufacturer and compensates for real life differences from the actual dimensions. The biggest differences has to do mostly with tire flex or expansion at speed. RPM is real

JZ - 10-14-2019 at 10:50 AM

Quote: Originally posted by PaulW

Goat
The rev per mile is actual from the manufacturer and compensates for real life differences from the actual dimensions. The biggest differences has to do mostly with tire flex or expansion at speed. RPM is real

If you got a tape measure out it's gonna measure closer to 35 than 34. Are you denying this?

PaulW - 10-14-2019 at 11:20 AM

dimensions and rpm do not agree. rpm is based on test data with the manufacturer's load and rim choice. RPM is always more accurate.
If you go to the trouble to measure the circumference with appropriate math by rolling the vehicle for one tire evolution the result will be closest to the RPM. The manufacturers use a dynamometer to measure endurance and wear and one of the of parameters measured is the RPM.

JZ - 10-14-2019 at 11:21 AM

You didn't answer my question.

PaulW - 10-14-2019 at 02:08 PM

Don't have a new tire to measure.
Best I can do is believe the manufacturer.