Dually Tires - Can't decide..
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Senior User
Joined: Oct 2001
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From: Florida
Dually Tires - Can't decide..
My 87 F-350 (460/ c-6) with a 3.55 rear end now has 215/85/16 tires on it. I'm about to take off on a 4,000 mile trip pulling a 20' enclosed cycle trailer.
Problem is the current Fireston SteelTex radials have great tread but minor dry-rot on the sidewalls. I don't need these blowing apart at 3am in the blackhills of SD. So, I like Michelin but everyone carries the 235 not the 215. Here's the questions:
1. Based on my math - the difference in diameter will move my 3.55 ratio to about 3.40 - should I be concerned? (motor is new with a torque mild cam, holley 600 with Elderbrok aluminum intake and dyno was 340hp with about 500 lbs. of torque)
2. Alignment - I just had this thing aligned with new radius bushings, other stuff installed - will the extra height of this tire throw anything out of whack?
3. Width between duals - I've got 1.2" of space between the duals now with no load on them. 215=8.46" and 235=9.25" so that leaves .40" clearance. When it gets a load from the trailer tongue weight - do you think it will touch?
Thanks in advance for the help with any or all of this. Sorry for the long post.
Problem is the current Fireston SteelTex radials have great tread but minor dry-rot on the sidewalls. I don't need these blowing apart at 3am in the blackhills of SD. So, I like Michelin but everyone carries the 235 not the 215. Here's the questions:
1. Based on my math - the difference in diameter will move my 3.55 ratio to about 3.40 - should I be concerned? (motor is new with a torque mild cam, holley 600 with Elderbrok aluminum intake and dyno was 340hp with about 500 lbs. of torque)
2. Alignment - I just had this thing aligned with new radius bushings, other stuff installed - will the extra height of this tire throw anything out of whack?
3. Width between duals - I've got 1.2" of space between the duals now with no load on them. 215=8.46" and 235=9.25" so that leaves .40" clearance. When it gets a load from the trailer tongue weight - do you think it will touch?
Thanks in advance for the help with any or all of this. Sorry for the long post.
Post Fiend
Joined: Jun 2002
Posts: 13,873
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From: Atlanta GA
Dually Tires - Can't decide..
My boss always puts P215/85R16 Michelins on his Dodge dually (about $1100 for six tires installed) and gets about 60K out of them. This is the standard size for the Dodges and this is a VERY common size. Maybe you need a new tire store.
#2=no
As for ratio change, I know the math says a tire 1.33 inches bigger, in real life it will probabkly be 1/2 that and it differs from tire OEM to tire OEM.
What you have to worry about, after the tire breaks in is the radial budges at the bottom of the tires touching each other AND stuff getting stuck between the duals because they do not have a big enough exit area.
Stones stuck between the two tires will break the cords and lead to blowouts. You can easily force a 1 inch stone between two duals just by driving over it. Throwing a 1 inch stone at 800 rpms (wheel speed) can do a fair amount of damage to your truck or the car behind you. From working at Ryder, I sort of remember there being Federal rules about how close sidewalls could be to avoid this type of thing.
#2=no
As for ratio change, I know the math says a tire 1.33 inches bigger, in real life it will probabkly be 1/2 that and it differs from tire OEM to tire OEM.
What you have to worry about, after the tire breaks in is the radial budges at the bottom of the tires touching each other AND stuff getting stuck between the duals because they do not have a big enough exit area.
Stones stuck between the two tires will break the cords and lead to blowouts. You can easily force a 1 inch stone between two duals just by driving over it. Throwing a 1 inch stone at 800 rpms (wheel speed) can do a fair amount of damage to your truck or the car behind you. From working at Ryder, I sort of remember there being Federal rules about how close sidewalls could be to avoid this type of thing.
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Senior User
Joined: Oct 2001
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From: Florida
Dually Tires - Can't decide..
Thanks - thet cost from Sam's Club is about 200.00 less - that's probably why - they don't carry as big of an inventory. I'm sure I can get them elsewhere but I'm also interested in seeing a modest increase in mileage. Even a 2-3% increase over 4000 miles adds up at the current 7-8 mpg I'm seeing.
Thanks again for your repky.
Thanks again for your repky.
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