255/85R16's on a 1st Gen Dually?

[AKimmel]

Does anyone out there have or know of a 1st Gen running 255/85R16's on the factory steel wheels? I have an 89 chassis cab 4x4 that I would like to put that size tires on, but don't know if they will rub together on the rear. Also has anyone ran this size without a lift, and not had any problems, rubbing, etc. Going off my past single wheel trucks, I think they should clear no problem, since thay set further in than on a single wheel. Thanks, Alex

 

[dpuckett]

Actually, if you look closely, you will see that the dually wheels dont run any different track than SRW wheels in front. That is what the adaptor is for.



That said, the only thing I can tell you is to put some on wheels and see how close they come. With the 235s I've had, I have had 1-1/2 to 2" between the tires, depending on the brand. If you haul heavy, you might consider 19. 5s- no clearance issues anywhere. If you keep it light, you may do ok.



Daniel

 

[pepecat]

well the 255/85 tires are not as wide as a 265/75 r16. The 255's are skinnier and taller! I have seen people run 265/75 so I would imagine that 255/85 will work if inflated to the max.

 

[AKimmel]

Actually, if you look closely, you will see that the dually wheels dont run any different track than SRW wheels in front. That is what the adaptor is for.



That said, the only thing I can tell you is to put some on wheels and see how close they come. With the 235s I've had, I have had 1-1/2 to 2" between the tires, depending on the brand. If you haul heavy, you might consider 19. 5s- no clearance issues anywhere. If you keep it light, you may do ok.



Daniel

I haven't actually measured it, but it seems on my dually, when you stand on the tire, to say wipe the windshield, my feet are barely reaching the tire. On the single wheel trucks I have/had it was actually pretty comfortable standing on the tire. Thanks for the responses. Alex

 

[CLiberty]

I have a SRW with 255/85`s, no rub in the front.

 

[bmoeller]

Tires will probably touch in the rear without spacers or switching to the newer 2nd gen rims that originally came on trucks with 235/85/16 tires. Deeper offset. I have 2355s inplace of the stock 215s, and I can't get my hand in between them at all. 1"-1 1/2" at the most for a gap. Tires at max PSI, and no rubbing with over 2K# on the back of the truck.

 

[dpuckett]

2nd Gen rims wont fit- holes aint big enough for the lugs.



I also thougth of something else- the dually rims on front are dishing out, and the SRW wheels are dished in a little. That could be your difference in standing on the wheel.



-DP

 

[tugboatphil]

Please forgive me in advance, if I am putting out bad info. I rarely try to answer a question seriously.



If my tire knowledge is correct, the first number (255) is the profile height of the tire, from the rim to the tread. The second number (85) is the width of the tread, from inside to outside. and the last number is the diameter of the wheel.



This being the case, going from a 235 to a 255 would not change the distance between the rear tires. However, going from an 85 series to a 75 series is increasing the tire width, and decreasing the distance between the rears.



My door sticker says my 93 D350 should have 215x85-16 and I run 235s, because they were on there when I bought it. I have no problem with the rear tires.



OK, now I'm switching back from serious question answerer to my previous position as Forum Smart Aleck.

 

[cerberusiam]

Please forgive me in advance, if I am putting out bad info. I rarely try to answer a question seriously.

If I had a nickel for every time I tripped on my tongue... ... !! :-laf :-laf







Ya got it only slightly backwards tugger. The first number (255) is the width of the tire face. The second number (85) is the height of the sidewall expressed as a percentage of the face width. ie . 85 x 255 is the height of sidewall.

 

[tugboatphil]

Then why is a 50 series wider than a 60, which is wider than a 70..... ??

 

[cerberusiam]

Then why is a 50 series wider than a 60, which is wider than a 70..... ??

Remember what I said about tripping on my tongue... . :-laf :-laf



Clarification -



First number is section width not face or tread width.



Second number is the aspect ratio, or the sidewall height as a percentage of section width.







Section width and tread width may or not be the same depending on manufacturer and tire style but section width is section width no matter the aspect ratio, manufacturer, style, etc. A 255 is a 255 whether it is a 85 or a 65 aspect ratio, a Michelen or BFG. However, you may not see or be able to measure that on the tread because of tread design.



The second problem comparing series of tires is the general shape of the tire when the aspect ratios shrink. There is much less flex and spring in the sidewalls at 45 than 65 so the transition from face to sidewal is more abrupt or square to keep the tire shaped correctly. The face is relatively flat all the way across instead of rounded at the corners like taller tires. The section width, internal shape and dimension of the section may be exactly the same between a 235/85 and a 235/45 but set side by side the 45 will seem to be wider, however, given the construction, style, and manufacturer is the same the contact patch under load should be almost identical. Change tire manufacturers and that goes out the window. Tire tread design and width is another whole subject that has many variables depending on use, size, rating, etc.





And you thought tires were an easy subject... ... .

 

[tugboatphil]

My head hurts... .



It's easier being a dunce. Now where's my pointy hat??