Help with tire selection.

[Rfhimes]

Hi guys/gals, sorry if this question has been answered before. I'm brand new to the board and this is my first post. I'm having trouble with the search on the board. I just recently purchased a 1970 C10 short bed pick up, pretty much stock but it does have 6 lug rally wheels, 15X8 size. It now has 235/75/15 tires that are worn and need to be replaced. My plan is soon to go with the 4/6 drop kit and the front disc brake conversion, power booster and front sway bar all offered by Early Classic. I don't want to change the rear axles to convert to 5 lug. Early classic has the 6 lug front rotors. I asked Early Classic to give me a recommendation on tire size they said 245/60/15 for the front and 275/60/15 for the rear. I respect their recommendation but thought I'd ask what all of you thought about this tire selection? I don't want to waste money buying the wrong tires. With my present size tires my speedometer is reading about 10 mph slower than my actual speed. Could that be my tire size?
Thanks for the help and your opinions.

[Fitz]

Originally Posted by Rfhimes

Hi guys/gals, sorry if this question has been answered before. I'm brand new to the board and this is my first post. I'm having trouble with the search on the board. I just recently purchased a 1970 C10 short bed pick up, pretty much stock but it does have 6 lug rally wheels, 15X8 size. It now has 235/75/15 tires that are worn and need to be replaced. My plan is soon to go with the 4/6 drop kit and the front disc brake conversion, power booster and front sway bar all offered by Early Classic. I don't want to change the rear axles to convert to 5 lug. Early classic has the 6 lug front rotors. I asked Early Classic to give me a recommendation on tire size they said 245/60/15 for the front and 275/60/15 for the rear. I respect their recommendation but thought I'd ask what all of you thought about this tire selection? I don't want to waste money buying the wrong tires. With my present size tires my speedometer is reading about 10 mph slower than my actual speed. Could that be my tire size?
Thanks for the help and your opinions.

The formula for determining the height of a tire when the width is in millimeters is as follows:

width in mm X 2 x aspect ratio /25.4 + rim diameter = height in inches.

the recommended tire by ECE was 245/60/15 so
(245 mm)x 2 x0.60/25.4mm per inch + 15=26.57 in tall

I run a 255/60/17 tire in front and a 275/60/17 in rear with the ECE 4/6 drop kit with no problems.

And, yes, your speedo reads low because of the tire size.

[BigMike]

That is exactly what I have on mine but with 7" front wheels 10" out back running the 245/60/15 & 275/60/15 tire combo with a 4/5" drop. I have seen guys on here use the 275/15's on 8" rims as well.

Eventually I will go another inch lower all around.

[Rfhimes]

Awesome , thanks BigMike, your truck looks sweet!

[BADAZ chevy guy]

Here's a cool website where you can compare tire sizes. Select the 'Overlay' option for a better view.
And Welcome to the forum!

http://www.tacomaworld.com/forum/tir...5r15-325-55r15

[Rfhimes]

Thanks for the response, cool link. I appreciate your response.

[mikewoods]

Trucks look great! Thanks for posting, this is exactly the information I was seeking today.

[Coursey]

I had the same question.

I am worried that the 245/275 will produce a .7" rake to the truck.

With the 4/6 drop the truck is setting with a little rake already and dont want to add to it much.

Would a 255/60 and 245/60 be a better combo?

[Mike C]

Averaged over the length of the truck there is not a whole lot of difference in tire height you are talking about. I have 27" front tires and 29" rears. The front is dropped 4.5" and the rear 7". And I KNOW people are getting tired of this pic, but it seems to answer lots of questions...

(ps: at some point if you want to go different wheels and tires you will REALLY wish you had switched to 5 lug!)

[engineer_gregh]

One more thing to consider is your rear end ratio and transmission. If you are going to do interstate driving at 65 mph or more 27" tires will turn more rpm's than a 29" tire. If you have an overdrive transmission not as critical.

[leftybass209]

Originally Posted by Mike C

And I KNOW people are getting tired of this pic, but it seems to answer lots of questions.

I only get tired of pictures when they aren't relevant like someone asking for green shortbeds with 5/7 static drops and then someone posts a red long bed bagged on 20's. " Happens more on Facebook though.

To the op- tire size is very subjective. Yes they will work and look fine to some people, but search that tire size on rallies because YOU may not like them and that's what matters. Rear axles can be re drilled, hubs turned down, and bearing area resurfaced for less than what new axles cost.

[67 chevelle]

I would go with early classics recommendation ,,, they have done lots of them ,,, another reason you speedometer is off is that someone changed the transmission , easy fix with a new gear on the bullet the cable attaches to at the transmission

[Pistol Pete]

I am in the same boat shopping for tires... This is another good site just to help compare sizes side by side...

http://tire-size-conversion.com/tire-size-calculator/

It shows pics and also specs... Been helpful for me... It does also show what each tire speed is compared to the other... Might be right what you are looking for...