Wheel Diameter size
Wheel Diameter size
I do not know the forumla to calucalte diameter sizes but I want to know if 245/45/18 is the same as 245/35/20.
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maxnix
- Posts: 22627
- Joined: Mon Jul 22, 2002 8:11 pm
- Car: 1995 Infiniti Q45
1995 Infiniti Q45t
2000 Infiniti Q45
Tire Rack
Go to Tire Rack and view the specifications chart for the tire you want. Normal Q Diameter unloaded is 26".
Do pay attention to the load capacity, as 95 (1521lbs) is the minimum for the Q. 98 is better.
Also, if the maximum load carrying capacity is achieved at 51psi, you probably have a really weak (single ply) sidewall.
Do pay attention to the load capacity, as 95 (1521lbs) is the minimum for the Q. 98 is better.
Also, if the maximum load carrying capacity is achieved at 51psi, you probably have a really weak (single ply) sidewall.
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
245 x 0.30= 73.5 mm sidewall x 2= 147 mm for both plus the 20" wheel [20 x 25.4= 508mm ] so 508 + 147= 655 divided by 25.4 equals 25.787" LESS the deflection of the bottom of the tire caused by the loaded weight ......which on a 20" would be smaller compared to a soft [higher] sidewall.
How much does a 3" high [on a 20"] sidewall deflect vs a 15" wheel's 5.5" high unloaded sidewall.............the amount of weight is nearly the same except for heavier wheel and tire.
Since the size of the contact patch is equal [if equal pressures are used] and equal weights are present a rough approximation is 3/5.5= 0.545 x what ever the 15" wheel/tire deflected.
How much does a 3" high [on a 20"] sidewall deflect vs a 15" wheel's 5.5" high unloaded sidewall.............the amount of weight is nearly the same except for heavier wheel and tire.
Since the size of the contact patch is equal [if equal pressures are used] and equal weights are present a rough approximation is 3/5.5= 0.545 x what ever the 15" wheel/tire deflected.