Tire cracks, advice needed...

[tomr]

Hi again all: One of the previous owners or my '75 D21 Brave changed it over to 16" rims. Even though the tires look like they were hardly used, dangerous looking cracks are evident. I'm just checking to see if my intentions are ok. Presently, there are LT245/75 16" tires load rating E. The rims are stamped with a 2500lb load maximum, and the numbers 16x6K as well as D-166 4. When I pulled off the funky chrome covers, I expected to find a rusty mess. Instead, I found seemingly brand new rims with shiny gray paint  : Sorry for beating around the bush a little, but I'm just fearful that this particular wheel/tire combo is causing the cracking...see pics below, and thanks for any replies  ;D

[89Elanden]

I think the problem is more with the age of the tires than the size. None of the pictures you posted showed the DOT date stamp code but I would venture to say if you check the date code the tires are more than 6 years old. I would replace them all, and invest in whatever the correct size was originally and get the correct size rims. The cracking is dry rot, comes from sitting all the time in contact with ground, exposure to elements, U.V. etc.

[89Elanden]

Now that I look again the 1st picture has a date code. before 2000 it was a 3 digit code, after 2000 4 digit. 1st 2 digits are the week of the year 1-52, 3rd and or fourth is the year.

[JDxeper]

I replaced my 8R17.5 tires and rims with 235/85/16.  The rims were funky grey also.  The 235/85/16 was selected because they have close to the same revs per mile as the 8R17.5 and they have good clearance for the duals. Speedo  is nearly the same.  As indicated pay attention to the date code and the load range.  Do a tire search and you will find a wealth of information. But it looks like tire replacement time.
JD

[89Elanden]

12th week of..... 1998? 1988?

[ibdilbert01]

Too much dry-rott for my comfort, I'd call it Replacement Time.         These rigs are just too heavy to take this kind of chance.     

[tomr]

Thanks for the speedy replies folks. I'm definitely going to replace them before I go anywhere. Now I'm debating between the 245/75's that are on it now, and 235/85's. The 245's are 30.5" in diameter and the 235/85's are 31.7" in diameter. Would the bigger diameter be "better" overall? Also, I suspect the 235's are better suited to 6" wide rims ?
Also, thanks for the date code advice...I didn't even think of that 

[JDxeper]

I believe that the 245/75/16 have a wider foot print than the 235/85/16.   Be sure you have a space between the duals so you won't have a heat build up in the tires.  mine are load range E.  I think I paid about $120 each for the 235/85/16.

[tiinytina]

yes on replacement time! better safe than sorry. Met up with a guy at an RV place in for major undercarriage work... blown tire took out chunks of his grey and black water tanks, water lines and a good chunk of the wheel well.... Jokingly... he said the rig left quite a skid mark...
Tina

[tomr]

ok...I began the replacement chore, starting with 2 new front tires. Then I removed the rear rims, and the fun started. Yup...the inner rear rims are 17.5", while the outers and the fronts are 16". What a pain !! Of course the 17.5" inner rear tires are the worst. Now I have some different concerns. On one hand, I could buy 2 16" rims and get rid of the 17.5's...BUT I'm concerned about the space between the duals. With 245/75 16's (size I just bought for the front), there seems to be about 3/4" of space between them. Is that enough? Did some previous owner already try 16's ? etc etc///
Of course I could buy 2 17.5" tires and keep things as they are.
Obviously, I see wisdom in having all tires the same. The 16's and 17.5's seemed to be the same diameter. They are 8R17.5LT while the others are 245/75-16.
Sorry for the rambling...

Tom

[tomr]

I guess I'll reply to my own post, while trying to ask a more specific question. Here's my situation: after purchasing 4 LT245/75R-16 tires (the size that were on the rig when I bought it) I discovered that the rear inner rims are of the old original 17.5" variety. My plan is to purchase 2 more 16" rims. However, in dual fashion, the 245's only have around 3/4" of space between the tires. I'm afraid that this is not enough. Therefore, I plan on purchasing 2 LT215/85R-16 tires for the inner rear. The diameters are slightly different (30.46" vs 30.38") but the narrower width should give me enough space between the tires. I can't return the 245's so this is my next best option. Will this work??
Thanks
Tom




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[salplmb]

hey jd,
i have been trying to change my tire size for years. did you use the same rims? i have been told that there is no other rim that will fit this rig. i even asked stockton wheel if they could make some and they said no. what brand tire did you use? 8r17.5 tires don't have allot of selection.
thanks for any info.
sal

[DanielTBolger]

I fond som alco 19 for mine winny  I seen som dodge 400 had soon 16.5 on them with that bolt patern

[JDxeper]

Tire size.  I used a 16" 8 hole coined rim came from fords and Dodges in the 70"s.  Lots of information on the forum regarding the rim swap.  Front disk brakes have been a problem for some.  do a thread search and them send me an e-mail if you have question. I posted pictures of before and after to show rim clearance on the brakes.  Had no trouble finding rims but finding rims that were not bent was a problem.  Went through about 15 rims or more to find 7.  Then found a source for new one and about the same cost after sand blasting and cleaning.I have some Cooper tires and some Goodyear. The 235/85/16 matched close to the 8r17.5 as far as overall diameter, and revs per mile,( speedo and rear end considerations) they have a wider foot print but still good clearance for the rear duals.  Lots of opinions , do your research.  JD  78Brave rg23