Anyone ever gone from the 265/75R16 to the 235/80R16? I presume you can do it on the stock rims. I have an '03 F350 CC LB 4X4 SRW 6.0L and need new tires soon. Presume all things are equal - no changes to the truck, same load range (LR E), same air pressure, etc.

The reason I am asking is I am wondering a couple of things

1.) Will the ride improve? Now, don't flame me about buying a 1-ton truck and expecting it to ride like a Caddy. I am just wondering if the 235/80's higher sidewall will give a slightly softer ride. I rather like the way my truck rides but if the 235s are a little more forgiving, then all the better.

2.) Will it affect fuel economy? Now, don't flame me about buying an 8,000 lb vehicle and expecting it to get the fuel economy of a Prius. I am just wondering it the smaller contact patch will decrease drag enough to affect the mpgs. With fuel prices what they are, it is worth considering.

3.) Do the 235s do better or worse in the rain and / or off the road? Not talking about going mudding or hitting the local Off Road Park but I do get off the pavement on almost all of my jobsites (I am a Commercial General Contractor).

4.) I forgot to look up the diameter (or circumfrence) of the two wheels to compare for the sake of speedometer error but I presume they are close enough for government work.

I am not locked into anything at all yet, I am just looking into which way to go. I will almost certainly go with a Michellin LTX M/S LR E on the truck. I do a TON of highway driving but still need some off-the-pavement ability and I have had a lot of folks say how much they like the LTX M/S. I am not trying to start a tire war - again - just looking for opinions and experience with the switch to the 235s. If I don't see any compelling responses in the affirmative, I will likely go with the stock size for my truck (stay with the 265s).

Thanks in advance,
Big

 

Just some quick math I did... 235/80 has about 7.4" (80% of 235mm) of sidewall and 265/75 has about 7.8" (75% of 265mm) of sidewall. The 235 is also about 0.85" shorter than the 265. These are calculated numbers, actual sizes will vary a bit with manufacturer.

 

I mounted some 235/85/16 winter tires on some factory wheels no problem. They work well on snow and ice because you get more ground pressure (same weight / less area = increased PSI) so better traction.

1.) I don't know if the ride really improved, but did seem to handle better. The 235/85/16 tires are narrower than the 265/75/16 tires and do not seem to get pulled into any ruts or cracks in the pavement. Should have about the same side wall height due to nearly the same overall diameter (+/- 1/4") and same rim size.

2.) Fuel economy should increase because of less rolling resistance, but may not be enough to measure.

3.) The 235/85/16 should do better in the rain since the narrower tire will have less likelyhood to hydroplane due to the smaller area. This will greatly depend on tread design. Both sizes of tires have good all-season, all-terrain, and mud tire designs available.

4.) Only about a 1/4" difference in height, but may vary slightly by manufacturer and tire design.

235/85/16 in the E range will have a rating of 3042# whereas a 265/75/16 E range will have a rating of 3415#. This could affect you if you haul heavy loads, but the older F-350's only used to come equipped with 235/85/16 and I never had tire problems when hauling 3,700# in the bed of the truck.

 

I'll bet you won't be able to tell the difference. The tires are for all practical purposes the same height, so the sidewall height will be the same too. The 265's will displace a little more air so the wind resistance will be greater, but hey, you're driving a barn on wheels anyway. Look here for tire dimensional data www.coopertires.com

 

BTW, I assumed you meant 235/85/16 rather than 235/80/16.