3 ms·

The upcoming Cadillac Escalade IQ is going to have an optional 24" wheel fitment. With the 50mm sidewall, this makes the total outside diameter of the tire 35"

by MrFoof 3y ago

The upcoming Cadillac Escalade IQ is going to have an optional 24" wheel fitment. With the 50mm sidewall, this makes the total outside diameter of the tire 35". That's the same tire diameter as you'd put on a rock crawling Jeep Wrangler to take to Moab, but it's instead on a (estimated) 8500lb (3855kg) full-size luxury crossover marketed as an "executive" vehicle. For comparison, the Hummer H1's tire outer diameter was 37". We're quite nearly to that level of insanity. I'd reckon just a tire is going to weigh nearly 50lbs (22.6kg), with the wheel about the same. I can't imagine how "fun" changing a 100lb wheel+tire is going to be when rotating tires. Moreover, the reality is the cost of the those tires will be comparable to near R-compound top-end performance car tires. Never having personally considered tires/wheels that weighed anywhere near this, I wonder what the point was when shops had to get entirely new wheel balancing machines, etc. to adequately accommodate these ever larger sizes and weights. The battery impact for an EV is also going to be substantial, as is the impact to braking performance. It's really just maddening.

profile53 3y ago
50mm sidewall /25.4mm/in = 2 in sidewall 24” wheel + 2 in above wheel + 2 in below wheel = 28” diameter, which seems much more reasonable. Am I missing something?
- MrFoof 3y ago
  Yes. The sidewall only accounts for a specific section of the side of the tire. You're excluding the portion which has to mate with the outer diameter of the barrel of wheel, as well as the entire outer tread. There's a LOT of material there in those two parts that aren't, "sidewall", nor accounted for in the size code. For example, I have 35mm sidewall sports car tires on 20" (only wheel offered by the manufacturer) diameter wheels. That would be less than 23" if we calculated as you did. The actual total diameter of an inflated tire though is ~27" (26.947") per the tire manufacturer (Michelin). I confirmed my assertion that it's 35s by running it through a tire diameter calculator (I do track days), and looking at outer tire diameters for tires for 23" wheels as a sanity check. Moreover, several media outlets (Autopian - partly run by a Jeep fanatic - The Drive, others) agree with me -- they are indeed 35". --- To be fair, for off-road tires, they're usually coded different. For example, a Hummer H1 which indeed has a 37" outer diameter tire, is coded as 37X12.5-16.5. But the Escalade IQs tires are coded as normal passenger tires, or 275/50R24.
  - profile53 3y ago
    That is actually super interesting, thank you for explaining how that works — I appreciate the thoroughness. Agreed that 35” tires on an SUV is absolutely insane.

by MrFoof 3y ago

profile53 3y ago

50mm sidewall /25.4mm/in = 2 in sidewall 24” wheel + 2 in above wheel + 2 in below wheel = 28” diameter, which seems much more reasonable. Am I missing something?

MrFoof 3y ago
Yes. The sidewall only accounts for a specific section of the side of the tire. You're excluding the portion which has to mate with the outer diameter of the barrel of wheel, as well as the entire outer tread. There's a LOT of material there in those two parts that aren't, "sidewall", nor accounted for in the size code. For example, I have 35mm sidewall sports car tires on 20" (only wheel offered by the manufacturer) diameter wheels. That would be less than 23" if we calculated as you did. The actual total diameter of an inflated tire though is ~27" (26.947") per the tire manufacturer (Michelin). I confirmed my assertion that it's 35s by running it through a tire diameter calculator (I do track days), and looking at outer tire diameters for tires for 23" wheels as a sanity check. Moreover, several media outlets (Autopian - partly run by a Jeep fanatic - The Drive, others) agree with me -- they are indeed 35". --- To be fair, for off-road tires, they're usually coded different. For example, a Hummer H1 which indeed has a 37" outer diameter tire, is coded as 37X12.5-16.5. But the Escalade IQs tires are coded as normal passenger tires, or 275/50R24.
- profile53 3y ago
  That is actually super interesting, thank you for explaining how that works — I appreciate the thoroughness. Agreed that 35” tires on an SUV is absolutely insane.