Tire Width...Using a 215 vice a 235.....pros?....cons?

Here are the options:

LT215/85R16
LT225/75R16
LT235/85R16
LT245/75R16

I'm thinking that if you are going from an ST225/75R15. then the easy choice is LT225/75R16. Only the diameter is an issue - and it will need 1/2" more clearance in the vertical direction.

There is a huge difference between the 2 sizes you are comparing. The 215\75s are much smaller. Three inches less overall diameter and 1.5" shorter sidewall for example. They will look tiny compared to the 235\85s. See below.

235\85r16
Section Width: 9.25 in
Rim Diameter: 16 in
Rim Width Range: 6 - 7 in
Overall Diameter: 31.73 in
Sidewall Height: 7.86 in
Radius: 15.86 in
Circumference: 99.68 in
Revs per Mile: 655.57/mi
Actual Speed: 62.14 mph 100.00 kph

215\75r16
Section Width: 8.46 in
Rim Diameter: 16 in
Rim Width Range: 5.5 - 7 in
Overall Diameter: 28.70 in
Sidewall Height: 6.35 in
Radius: 14.35 in
Circumference: 90.15 in
Revs per Mile: 724.82/mi
Actual Speed: 56.20 mph 90.45 kph
Speed Variance: 10.56% too slow.
Diameter Variance: -9.55%

If you want to go to a narrower tire and keep the same overall diameter you need to go to a higher profile ratio. You won't find, nor want, much higher than an 85 that you have. You'd have to go to a bigger rim.

On my previous trailer, I had to go with 215's to clear the shock absorber. I would have gone with 235's, given the choice, for more weight margin, but didn't have that option. I was upgrading from 15 to 16" wheels and the 215's met what I needed, so I ended up going with them. Traveled on those 215's thousands of miles with no issues.

Oh, the other issue is 235's might require a wider 16" wheel than the 215's.

And I believe the "R" means "Radial" rather than "Ratio" IIRC.

The 235 number is the width in millimeters.

There are 25.4mm per inch, so 235mm*(1in/25.4mm) = 9.25"

The 85 number is the aspect ratio (sidewall height/width) which represents 0.85 ratio. So 235mm*0.85 = 199.8mm.

Converting the 199.8mm height to inches 199.8mm*(1"/25.4mm) = 7.864".

Since the side wall height has a top and bottom, the overall sidewall height is 15.73".

A 16" wheel + 15.73" of sidewall height means the tire is 31.72" tall unloaded.

The larger tire size typically has more capacity, so I would go with the larger size if they will fit.

Hi,

The 235 is the width, the R is the ratio of width to height. I chose to replace my wheels to have enough offset to use 235/85 R16 This gained me 1.25 inches in height and improved gas mileage on my unit. The wider tire has less rolling resistance and more carrying capacity istr.

I would go with the 235's myself. That would leave the option to try 215 the next time round the block.

Fitment and load rating are the issues with deciding 215 vs 235 etc.

215 & 235 are width measurements. The 75 vs 85 is the width to height ratio.
Each combination will have it's own max load rating.

Search Tire Rack for a full explanation.

Cruz-in are you sure u don't mix numbers op, as I believe the first tier 235/85-16 to be a lot taler than 215/75-16 as the second lot of numbers indicates the % in hight of its with, 235/75-16 more like same hight as 215/85-16. This is my understanding of the numbers.
Frank

I am not sure of Donn's remark, as I believe him to be quite knowledgeable?

I agree the 235-215 should be the width, and the 75 be the height.

Jerry

If the smaller tire has sufficient headroom in the load rating, then there is no particular downside to the smaller tire. It will wear faster, give a slightly harsher ride and the trailer will sit an inch or two lower. If you are OK with all that, buy the smaller tire. I would.

Brian