Tire ride question.

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Tire ride question. Would there be any noticeable difference in ride smoothness between a 70 and 75 series tire? I am talking about the same make and model tire except for the series.
 
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I find there is a lot more difference in the actual compound of the tire itself. I have the same size tires on all 4 corners of my car, but they're in different pairs. The tires on the rear ride harsher, even though they are the same size as the front pair.
 

ron350

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OK this is for a 1975 Chevy C10 short wheelbase truck that only sees light use. The rims are 6 x 15 and currently have 215/70R15’s that are way too short for the truck. This truck rides rough so I do not want to put a tire on that will make it worse.
 
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 Originally Posted By: ron350
OK this is for a 1975 Chevy C10 short wheelbase truck that only sees light use. The rims are 6 x 15 and currently have 215/70R15’s that are way too short for the truck. This truck rides rough so I do not want to put a tire on that will make it worse.
Tire construction and load rating would typically have a far greater impact than a 5% sidewall height difference. That said, all else being equal, the taller sidewall should help some. Whether it would be enough to be perceptible is questionable. If the truck isn't used for maximum weight loads, I'd suggest using the lowest load rating that is spec'd for a variant of the truck in question.
 
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The 75 series should have softer ride than 70 series tire, assuming all other things are the same, same width, same model, same pressure. But you will see a decrease in performance and handling with taller side wall tires.
 
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 Originally Posted By: ron350
OK this is for a 1975 Chevy C10 short wheelbase truck that only sees light use. The rims are 6 x 15 and currently have 215/70R15’s that are way too short for the truck. This truck rides rough so I do not want to put a tire on that will make it worse.
OK, a 1975 C10 originally came with either G78-15's, H78-15's, or 7.00-15's all inflated to 32 psi - except for versions that used a 7.00-16 (obviously not applicable here) or LR78-15's inflated to 28 psi front and 32 psi rear (all on a 6" rim) A couple of points: 1) Inflation pressure affects ride quality more than any other property. You didn't tell us what pressure you are running - and given that the tire size is completely different, that could be the source of the poor ride. 2) For some reason, Pickup Trucks and SUV's are designed with wheel well openings that are huge compared to the tires they put on. I partially suspect that this goes back to "What looks right" given that tires on pickups and SUV's are more marginal in size than passenger cars (Sometimes LOTS more marginal!!) So, please do not go by the size of the fenderwell opening as an indicator of what the right tire size is supposed to be. 3) The difference in ride quality between a 70 series tire and a 75 series tire is small compared to the difference between different tires - even within the same brand. So let's do some math: A G78-15 has a load carrying capacity of 1620 # at 32 psi - whioch has to be derated 10% because it is on a light truck = 1472 # To carry the same load, a P215/70R15 needs to have 35 psi, but a P215/75R15 needs 31 psi.
 

ron350

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Thanks for all the helpful replies now all I have to do is decide what size and brand 75R15 to buy. LOL The tires on the truck now are Grand Spirit Aqua-Flow 215/70R15’s that were supposed to have been the tallest Aqua-Flow tires they could sell me back then. To go to a taller Aqua-Flow they told me I would have to go with a stiffer truck tread pattern. Other than the rougher ride the AF did handle wet roads better and they lasted 10 years. The previous two sets of tires were Multi-Mile 215/75R15 and were over an inch taller than the Aqua-Flows and rode smoother. The only trouble with the Multi-Mile tires was that they were very loose in the rain not only on the truck but also on my 1986 cutlass.
 
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