New Tires 265/75/15

[Espy71]

Put on some new tires last weekend. Before the truck had 255/60/15 but they were way too small for me. I went with 265/75/15 instead. The truck drives so much better and on the highway it cruises at much lower RPM.

Up next is a white bed cover and maybe a fresh paint job on the interior. Then maybe pull the glasspacks and replace with Turbo mufflers. Right now it's a little too loud for my taste.

Later,
Espy.

[Sicklajoie]

Good choice on tire size. Fills in the wheelwells nicely.

[Southcity]

Originally Posted by Sicklajoie

Good choice on tire size. Fills in the wheelwells nicely.

^^agreed^^ - that truck looks really clean, are you able to post any interior pics?

[yuccales]

Great looking truck.

[Espy71]

Thanks guys. I will take some pics of the interior soon. The truck is in pretty good shape but there are still lots of little things to be done. Tonight I took the instrument cluster apart and started to paint it. I also went to Napa and they said they could match the Ochre color if I bring them the paint code then they will make a couple spray cans for me. I will also be ordering some new carpet and seals.

I just wish I had more time to get it all done.

Espy.

[Already Gone]

Originally Posted by Espy71

Thanks guys. I will take some pics of the interior soon. The truck is in pretty good shape but there are still lots of little things to be done. Tonight I took the instrument cluster apart and started to paint it. I also went to Napa and they said they could match the Ochre color if I bring them the paint code then they will make a couple spray cans for me. I will also be ordering some new carpet and seals.

I just wish I had more time to get it all done.

Espy.

Very nice truck and don't worry about getting it done because you will soon find out, your truck is never done, so enjoy it as you get it done.
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[jocko]

wow, looks great!! Beautiful truck and I like those tires - I'll be honest, I didn't think anyone made a 265-75, but I'm glad you found em, they look real nice. Have you adjusted your speedometer gear? While cruising at the same speed as before might appear that you're cruising at lower rpms, it might just be a case of your speedo being further off, which it would be with that big of a change in diameter. A 255-70-15 is around 30", I can only imagine a 265-75 has to be around 32-ish??? That will make your speedo read lower than actual (i.e. taller tire = more likely to get a ticket inadvertently...) Just curious. But then again, the 255s would have been a big leap from stock, so if it was off with the 255s, it's probably way off with 265-75s. You've probably already taken that into account, but just thought I'd mention it - I have a similar issue with my truck and one of these days I'm gonna have to get around to swapping out my speedo driven gear at the trans. I've been too lazy to do it so far because I checked with gps and know about how much to kentucky windage it... Ha. I'll probably get a(nother) ticket....

[Yooper truck]

Nice timing.... I was just pricing tires today. I have 255/60's on my truck now and was surprised how limited the selection is for this size. So I have a few Q's.

How much does this size effect your speedometer? How wide are your rims? Lower RPM's, on a tach or by what you hear?

Thanks!

[jocko]

it affects the speedo's accuracy the same way a rear gear change would.
Consider that if you start with a bone stock setup - the car (sorry, the truck!) will show a given speed based on trans output shaft rpm only - and this is a matched setup for the rear grar ratio AND tire diameter.

So, if you only change the tire diameter by increasing it - a single rotation of the trans output shaft will still result in the same angular rotation of the tire (i.e. number of degrees rotated through) - BUT, because the diameter is greater, when you roll that out over the ground, you will have covered more ground for that same trans output shaft rotation.

So, larger tire diameter = you will cover more ground for a given rpm - but your speedometer will not tell you that because it's only driven by the trans output shaft. So you'll be going faster than you think you are.

The opposite is true if you run a shorter than stock tire - you'll think you're really moving when you really aren't.

Amount of error is proportional to how much bigger or smaller your new tire diameter is than stock. Minor changes, most folks just live with it and mentally note the minor change with a gps.

As an example, on my DD, I went from a stock 265-75-16 tire up one size only to a 285-75-16. At 70 mph on the speedo, I'm actually doing about 75. Makes one susceptible ot gettin a ticket. I live with it on that truck, it's an 01 silverado. On my 66, however, the problem is a bit worse because I've made a bigger change in tire diameter from stock by running 235-75-15s now vice the original tiny tires.

Hope that helps.

[Espy71]

My Speedo was way off with the smaller tires. When going 70 my Speedo would read 80! I measured the tires before the install and they were just slightly more than 30 inches and after they were installed on the truck they are now 29 1/2 inches. When I used a GPS to track the speed my Speedo was right on 70 and the GPS showed 69. So I think I'm as close am I'm going to get unless I can get the 1 mph with a gear change. I'm pretty happy with it. I kinda knew I would be close because I've read so many other people on this site posting great info.

I only found two tires that came in the 265/75/15 I can't remember Whitten other brand was, maybe trial t/a something. Anyway without going to a 16 inch rim there are very few options in this size.

thanks for all the good info.

Espy.

[jocko]

Ha! No, that's about as close as you can get, glad to hear it. Now I gotta go fix mine. Or maybe it'd be easier to just smack my gps....

[jim-bob]

Originally Posted by Espy71

Put on some new tires last weekend. Before the truck had 255/60/15 but they were way too small for me. I went with 265/75/15 instead. The truck drives so much better and on the highway it cruises at much lower RPM.

Up next is a white bed cover and maybe a fresh paint job on the interior. Then maybe pull the glasspacks and replace with Turbo mufflers. Right now it's a little too loud for my taste.



Later,
Espy.

...what is the Width of these Wheels?
Thanks

[derotoreut]

I am doing a similar tire change with my '69 C/20. The PO had 275/60-15 tires (yes 8-lug 15's) on it. I just changed over to 17" rims and have 285/70-17's on it. Really fills up the wheel wells. The diameter difference is 4" bigger. I'm not sure what my speedometer will show. Haven't driven it yet, but I will check it with my GPS. For more info on tire size in relation to speedometer, try this website. Also tells you what tires are out there.

http://www.1010tires.com/tiresizecalculator.asp

[badfiero]

p265/75r15 tires are stock on the colorado so they are becoming more common. However if you check the specs they match a 31x10.50r15 coming in at 30.9 overall diameter. I have had 31x10.50r15 on my truck since 93. They fit great even with mine lowered 2" front and 4" rear 2wd.

[jim-bob]

Originally Posted by badfiero

p265/75r15 tires are stock on the colorado so they are becoming more common. However if you check the specs they match a 31x10.50r15 coming in at 30.9 overall diameter. I have had 31x10.50r15 on my truck since 93. They fit great even with mine lowered 2" front and 4" rear 2wd.

...What is your truck??

[Espy71]

The wheels in my picture are smoothies 15x8.

Rick.

[badfiero]

1971 c10 this is right after i bought it.