# Rotor thickness inside/outside **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [June 8, 2025, 9:55pm UTC](https://community.cartalk.com/t/rotor-thickness-inside-outside/200561 "2025-06-08T21:55:09Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [June 8, 2025, 9:55pm UTC](https://community.cartalk.com/t/rotor-thickness-inside-outside/200561/1 "2025-06-08T21:55:09Z")
Brakes have an occasional light rumble and I see inside disc is .350 and the other is .400. Pad thickness is ok. At least .250. There is a slight ridge on inside/outside. Is .050 disc difference cause for concern? ![image](https://global.discourse-cdn.com/cartalk/original/3X/2/b/2bd4b2da675368d8c972620040b01c0d581fcdbb.jpeg) ![image](https://global.discourse-cdn.com/cartalk/original/3X/4/1/41a9df05d1e5203f948bee41b94ccd9cf7ba05b0.jpeg) ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [June 8, 2025, 10:23pm UTC](https://community.cartalk.com/t/rotor-thickness-inside-outside/200561/2 "2025-06-08T22:23:16Z")
No. Cheap rotors can be that far off when new. Just be sure to check for a sticking caliper or slide pins. ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [June 9, 2025, 1:37am UTC](https://community.cartalk.com/t/rotor-thickness-inside-outside/200561/3 "2025-06-09T01:37:26Z")
looks okay to me ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [June 9, 2025, 7:51am UTC](https://community.cartalk.com/t/rotor-thickness-inside-outside/200561/5 "2025-06-09T07:51:54Z")
> [@Cavell](#): > > one web is .350 and the other is .400. By web do you mean disc? ---
**Author:** ![TwinTurbo](https://avatars.discourse-cdn.com/v4/letter/t/8baadc/32.png) [@TwinTurbo](https://community.cartalk.com/u/TwinTurbo)\ **Post date:** [June 9, 2025, 11:24am UTC](https://community.cartalk.com/t/rotor-thickness-inside-outside/200561/6 "2025-06-09T11:24:47Z")
> [@texases](#): > > By web do you mean disc? Those interconnecting structures between the rotor plates. They look fine to me. I’m used to seeing lots of flaking there. The rotor face looks like it needs attention however… ---
**Author:** ![jtsanders](https://avatars.discourse-cdn.com/v4/letter/j/c2a13f/32.png) [@jtsanders](https://community.cartalk.com/u/jtsanders)\ **Post date:** [June 9, 2025, 12:46pm UTC](https://community.cartalk.com/t/rotor-thickness-inside-outside/200561/7 "2025-06-09T12:46:23Z")
The ridges look large to me. After you machine the rotors, the ridges will be even more pronounced. I’d replace the rotors. ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [June 9, 2025, 12:57pm UTC](https://community.cartalk.com/t/rotor-thickness-inside-outside/200561/8 "2025-06-09T12:57:19Z")
> [@TwinTurbo](#): > > Those interconnecting structures between the rotor plates. Ok. I wouldn’t give their thickness a second thought. ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [June 9, 2025, 1:21pm UTC](https://community.cartalk.com/t/rotor-thickness-inside-outside/200561/9 "2025-06-09T13:21:23Z")
Find out what the discard thickness and or minimum machine to thickness is, and measure the thickness of the rotor disc, if above 0.030" from the discard thickness, then machine them, should only take about 0.010" (maybe less) from your description and the looks of them, they look like most normal rotors I see in my part of the world… Or if enough above the minimum machine to thickness -same thing, turn them… Or just replace them, your choice… lol That is of course if you can get them off without having to use a 5 lb hammer… ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [June 9, 2025, 1:26pm UTC](https://community.cartalk.com/t/rotor-thickness-inside-outside/200561/10 "2025-06-09T13:26:20Z")
> [@texases](#): > > > [@TwinTurbo](#): > > > > Those interconnecting structures between the rotor plates. > > Ok. I wouldn’t give their thickness a second thought. Cooling vanes.. ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [June 9, 2025, 2:37pm UTC](https://community.cartalk.com/t/rotor-thickness-inside-outside/200561/11 "2025-06-09T14:37:57Z")
> [@Cavell](#): > > Brakes have an occasional light rumble and I see inside disc is .350 and the other is .400 OK, now the question makes sense. I’d hold off doing anything until either the pads wear out or the rumble becomes significant. I’d replace pads and rotor in either case. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [June 9, 2025, 3:14pm UTC](https://community.cartalk.com/t/rotor-thickness-inside-outside/200561/12 "2025-06-09T15:14:48Z")
> [@jtsanders](#): > > After you machine the rotors, the ridges will be even more pronounced. The ridges are removed when machining rotors. [![](https://global.discourse-cdn.com/cartalk/original/3X/b/7/b795b3fb0416fd97447c3b5f92c01d7671bd029a.jpeg "Turning brake rotors on Atlas lathe. Pt.1") ](https://www.youtube.com/watch?v=FaXX8kxePbI) Tester ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [June 9, 2025, 3:40pm UTC](https://community.cartalk.com/t/rotor-thickness-inside-outside/200561/13 "2025-06-09T15:40:17Z")
Inner and outer planes have different thicknesses, sometimes it is by design, other times it is just a sloppy casting. In your case the difference is not a concern. ![image](https://global.discourse-cdn.com/cartalk/original/3X/b/3/b3c3db2350fac5dd218c715a04fcf3f47266e5ac.png) Look closely at the rotor below, the chamfered edge is a rough visual guide to discard thickness, if there is no chamfer remaining, the rotor is no longer useable. Follow up with a micrometer measurement. Your rotors appear to have a reasonable amount of material remaining, do you have a rotor micrometer? ![image](https://global.discourse-cdn.com/cartalk/original/3X/4/1/41ba9c84e16a3b200afd7444cc525dae53853f9c.jpeg)