AMT 20" tire sizes ???

[Goodwrench3]

Hi all:

Can someone explain why the tire sizes are so much different in some of the AMT 1/25 truck kits ?   In my photo, on the left is a tire from the recent Round 2 re-pop GMC "Miller Beer" Astro 95 kit.  On the right, that tire is from the Round 2 re-pop of the Kenworth K-123 cabover.  Supposedly they are both 20" tires -- but the diameter and width are very different.

I'm wondering from a scale perspective -- which is closer to scale ?   One of them is either far smaller than scale or the other is far larger.  

Thanks !

[37 caddy]

AMT tires are horrible?,years ago the tires that came with the MPC kits were the best,they came in the Mack kits the DM600 and the DM800,they were a softer type of rubber and fit nice and flush to the edge of the rim.You should have seen the tires that came with the Ertl kits,they were a 2 piece setup and were a shiny plastic type of rubber,later on when Ertl bought out MPC they started to use the better tires in their kits..I always used the fatter tires if i had any to spare,they just looked so much better.I cant explain why they use different tires in the kits today,must be the extra cost?. harvey

[Goodwrench3]

10 minutes ago, 37 caddy said:

AMT tires are horrible?,years ago the tires that came with the MPC kits were the best,they came in the Mack kits the DM600 and the DM800,they were a softer type of rubber and fit nice and flush to the edge of the rim.You should have seen the tires that came with the Ertl kits,they were a 2 piece setup and were a shiny plastic type of rubber,later on when Ertl bought out MPC they started to use the better tires in their kits..I always used the fatter tires if i had any to spare,they just looked so much better.I cant explain why they use different tires in the kits today,must be the extra cost?. harvey

 

RE:   "the tires that came with the Ertl kits,they were a 2 piece setup and were a shiny plastic type of rubber,"  --    yes !   I built an ERTL Transtar F-4270 kit with those two-piece tires !

I have learned just a short while ago that in my photo, the tire on the left is actually a "10.00-20".  The tire on the right is marked "11.00-20".   So the inside diameter (20) is the same, but the sidewall height is different (10.00 vs. 11.00).   So I guess both are correct as far as scale size, but they do actually represent different tire "sizes".

 

[Goodwrench3]

I've also learned this as far as which was a more common size (10.00-20 vs 11.00-20) in the mid-1970s:

"10.00x20 was the most common tire tire in the US for nearly three decades. 11.00 may have had a higher GVW rating over a 10.00, for one reason "

also --

"10/20 would be period correct for 1970's. 11/20 would be correct for vocational trucks. dumps low boys etc."

 

Edited January 19, 2022 by Goodwrench3
Added information

[OldTrucker]

The tires in my GMC Astro kit are terrible. Kit is dated 2004.

The wheels just drop loosely through the side that didn't have the spider.

Stuffed the tires with tissue to spread them a bit but they slide in over the raised center.

Are the tire sets Round 2 are selling any better? I hate to go that way as I would have to order them and with shipping it would be north of 20 bucks for them!

[Bills72sj]

23 minutes ago, OldTrucker said:

The tires in my GMC Astro kit are terrible. Kit is dated 2004.

The wheels just drop loosely through the side that didn't have the spider.

Stuffed the tires with tissue to spread them a bit but they slide in over the raised center.

Are the tire sets Round 2 are selling any better? I hate to go that way as I would have to order them and with shipping it would be north of 20 bucks for them!

I have two tricks for you.

Get some 3/8" foam backer rod to hold the sidewalls against the rim lips.

Or get some Moebius replacements.

[Goodwrench3]

The Moebius tires (and wheels) are really nice.

I used the AMT tires in the parts pack they produced on the IH Transtar 4300 and they fit really well.

 

[tbill]

I’ve been using aftermarket tires on my AMT kits, kit tires are just horrible, sadly, I’m getting low on good tires though…., and KJ isn’t making tires anymore……

[DRIPTROIT 71]

The tires in the new 4070a kit look pretty good to me as well. If those are the ones in the tire packs, I may get a set.

[Goodwrench3]

I haven't opened my new re-popped Round 2 4070A kits yet.

KJ isn't making tires anymore --  and it seems that the Moluminum web site is ka-put  ??

 

[Rockford]

And I thought I had problems with my 1/32 garbage tyres? I feel in good company. 

[peteski]

On 1/19/2022 at 4:43 PM, Goodwrench3 said:

The Moebius tires (and wheels) are really nice.

I used the AMT tires in the parts pack they produced on the IH Transtar 4300 and they fit really well.

 

While I'm not a prolific big-rig builder, I'm always on a lookout for good tires.  I bought this set and I'm not too impressed with them. The tread looks ok, but the pattern on the sidewall where it meets the tread looks weird to me, and it extends too far down the sidewall. Are there real tires out there with that type of pattern?  The cross section is also a bit strange (as if they should go on very narrow rims).  But I guess compared to all the really crappy tires that have been included with some kits, these aren't half bad.

My other gripe is the lack of any info molded into the sidewalls. I understand that there are issues with licensing, but why not just put some generic info like the type and size of the tire.  The blank sidewalls aren't very realistic.

My all time favorite truck tires are the real-rubber Michelin X tires included in the Revell Can-Do wrecker (and likely other kits).  Everything on those looks very realistic.

The Moebius 1:25 Big Rig Wheel and Tire Set also includes very nice tires. Those tires have nice tread, sidewalls with lettering on them, and a good looking cross section.

 

[Goodwrench3]

6 hours ago, peteski said:

While I'm not a prolific big-rig builder, I'm always on a lookout for good tires.  I bought this set and I'm not too impressed with them. The tread looks ok, but the pattern on the sidewall where it meets the tread looks weird to me, and it extends too far down the sidewall. Are there real tires out there with that type of pattern?  The cross section is also a bit strange (as if they should go on very narrow rims).  But I guess compared to all the really crappy tires that have been included with some kits, these aren't half bad.

My other gripe is the lack of any info molded into the sidewalls. I understand that there are issues with licensing, but why not just put some generic info like the type and size of the tire.  The blank sidewalls aren't very realistic.

My all time favorite truck tires are the real-rubber Michelin X tires included in the Revell Can-Do wrecker (and likely other kits).  Everything on those looks very realistic.

The Moebius 1:25 Big Rig Wheel and Tire Set also includes very nice tires. Those tires have nice tread, sidewalls with lettering on them, and a good looking cross section.

 

I agree the Moebius tires are nice -- but they really aren't what I would call "period correct" for 1970's era cab over trucks.  They are pretty much more "modern" tires.  Of course, while we're on the subject of gripes...  the AMT kits always have 10 what I would call "steer" tires.  The don't have 8 "drive" tread tires and 2 "steers".