Question for owners of older/shorter P-30's (or ANY tire guru in the group)..........

It's time to replace the steer tires - tread is great, no visible checking, but five years is long enough, considering bride, kids & grandkids as my cargo. (also have Steer-Safe)

Current full set of tires are 7.50R16's.
Contrary to some urban legends, I've had great service with my Michelin XRV's and plan to stay loyal to the brand. Unfortunately, XRV's are no longer available in 16".

The Michelin XPS is available and probably my next choice. Reviewing specs, if I go from the standard 7.50 to LT235/85/R16, I can go from Load Rating D to Load Rating E. (The D Rating works, but I figure any tire that has to work lower down the scale than its rated load is just added peace-of-mind.)

The 235/85's are within 3/8" of the old 7.50 tire diameter, but 1.4" wider (to be mounted on 6" Alcoa wheels).

QUESTION: Will wheel well clearances and steering/suspension geometry allow for this size replacement tire?..... Anything else I should be considering? (I normally don't rotate front-to-back so potential tire rub at the dual position is a non-issue. Also, the mounted spare is a 7.50, so it would remain an all-position spare & good enough in front to get me into town for a fix.)

"The 235/85's are within 3/8" of the old 7.50 tire diameter, but 1.4" wider (to be mounted on 6" Alcoa wheels"...
I don't have an answer, but I have a question: 1) Are the Alcoa wheels for the new tires currently carrying the 7:50s? 6" dia wheels don't seem WIDE enough for 235s. ??? If the tire, esp with a tall 85 aspect, is 1.4" wider it seems the wheel should be more than 6" wide.

Gunner,

Thanks for the reply.....My tire moxie is really limited so bare with me.....

My info came from the Michelin site. I think it says 235/85's are good for 6"-7" rims. In addition, the 245/75 calls for 7" rims, even though they more closely match 7.50R16 dimensions........I've got too much invested in the Alcoas to go back to steel rims just for a tire fit

What da ya think?.....I'm I reading this right, or have I once again got myself totally confused?

They aren't on a Barth, but:
Everybody in the old Land Rover off-road community replaces there 750R-16 with the now available 235/85-16s since you can't find the 750s anymore.
The 750s were the OEM tire on my 68 Land Rover. The 235/85 work fine under very tough off-road conditions on the 16'X6" wheels.
I'd still want to hear my tire professional's opinion tho.
Don

Thanks Don....Sounds like I can deduce that the 235/85's WILL fit 6" rims....Now I need to determine if the whole thing will work on a P-30 and if it will fit in a Barth wheel well!

(In case anyone is curious why I just don't go to a local, knowledgeable tire man for the answers, it's because I can't seem to find one!)

"My info came from the Michelin site. I think it says 235/85's are good for 6"-7" rims"...
Question answered - they are all right.
The bead (bottom) of the tires will be the same width as the 7.50s. Here is where I am confused: is the actual width of the tread 1-1/4" wider than 7.50s? If so, the tire is squeezed in 1-1/4" at the bead; conversely, the 7.50s were the same width as the 235s at the bead (6") and only 5/8" narrower halfway up?
Sounds like you don't have a problem. You're only talking about 5/8" (on the inside of the tire at its widest point - the tread) and you can eyeball that.

I put a pair of 235/85x16 on my 75-p30 the other day.Dont have many miles on them yet but I think it handles a lot better now. No clearance problems eather .Went from 8 ply to 12 ply alsow .

Questions asked - questions answered..all in just a couple hours.....

On my way to the tire store today....

Thanks for the input!

How did you make out Lee? Is there any FYI to pass along?

Had to order them Bill...a few days I'm told.
But, I think it's just as well....Watching the shop troops install some heavy truck rims, I had to cringe at what might happen to my Alcoas if they installed them....so ordered the tires in-a-bag-to-go......

There's a contract shop nearby that handles all the areas fire trucks - should be very familiar with aluminum wheels...I'll see if they can install them...(and as an additional benefit, I won't have to learn Farsi

I'll post update after I get a few miles on them.......

how did your 235 85s hold out?

Almost 4 years and 20K+ miles since this thread started, and I've been totally happy with the results. Not one tire issue since installed. The 235's work great on the steers (I'm still w/ 7.50's on rear).
Tread still looks about 90%, but just starting to show very minor sidewall cracking this year, so next spring will be R&R time. (ROI works out to about 6 cents/mile, less $200 residual value from a landscaper for his trailers - fair enough in my book.)

Next challenge: Unfortunately, it appears Michellin stopped making the XPS in a 7.50, so I'll need to go to 235's for the duals this time. Hope the Alcoa's give me the gap I need for 235-85's.

I know that brand loyalty discussions on RV forums usually starts food-fights, so suffice it to say that I've been partial to Michellins a long time...The ones on the Barth have reinforced that.......

FWIW: My short experience with my son's Barth last month has me pretty well convinced that Double Coins are not on my short list

quote:

Originally posted by Lee:
My short experience with my son's Barth last month has me pretty well convinced that Double Coins are not on my short list

Well, they are most assuredly on mine. You betcha.

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Oh.........you said short list.

reason for asking, we had 7.50s originally, mounted 235s in April and they were starting to rub after 1500 miles. No we did not overload or let the air pressure go down. we got steel rims with alu simulators. Got back to Raben Tires in Evansville IN and they were very nice and replaced all tires with 215/85R16s. Maybe finally all is straightened out and we can roll south for turkey day and the GTG. BTW they are Uniroyal Laredo. Will never ever get a chinese tire, should have went with Michelins too. oh well, save a dollar now, pay later.

You bring up a good point: Exactly how much daylight between sidewalls is enough?.
Seems like occasional sidewall contact (ruts, etc) ought to be tolerable, therefore any
airspace between tires in a fully loaded condition ought to be acceptable. Skinnier tires is one
solution, but to my way of thinking, it would be preferable to put the max amount of rubber on the road.

Who's got the answer?